diff --git a/src/java/org/apache/poi/hssf/usermodel/HSSFEvaluationWorkbook.java b/src/java/org/apache/poi/hssf/usermodel/HSSFEvaluationWorkbook.java
index 877a8f21de..6b8c30dc39 100644
--- a/src/java/org/apache/poi/hssf/usermodel/HSSFEvaluationWorkbook.java
+++ b/src/java/org/apache/poi/hssf/usermodel/HSSFEvaluationWorkbook.java
@@ -120,10 +120,29 @@ public final class HSSFEvaluationWorkbook implements FormulaRenderingWorkbook, E
 	}
 
 	public ExternalSheet getExternalSheet(int externSheetIndex) {
-		return _iBook.getExternalSheet(externSheetIndex);
+	    ExternalSheet sheet = _iBook.getExternalSheet(externSheetIndex);
+	    if (sheet == null) {
+	        // Try to treat it as a local sheet
+	        int localSheetIndex = convertFromExternSheetIndex(externSheetIndex);
+            if (localSheetIndex == -1) {
+                // The sheet referenced can't be found, sorry
+                return null;
+            }
+	        if (localSheetIndex == -2) {
+	            // Not actually sheet based at all - is workbook scoped
+	            return null;
+	        }
+	        // Look up the local sheet
+	        String sheetName = getSheetName(localSheetIndex);
+	        sheet = new ExternalSheet(null, sheetName);
+	    }
+	    return sheet;
 	}
-	
-	public ExternalName getExternalName(int externSheetIndex, int externNameIndex) {
+	public ExternalSheet getExternalSheet(String sheetName, int externalWorkbookNumber) {
+	    throw new IllegalStateException("XSSF-style external references are not supported for HSSF");
+    }
+
+    public ExternalName getExternalName(int externSheetIndex, int externNameIndex) {
 		return _iBook.getExternalName(externSheetIndex, externNameIndex);
 	}
 
@@ -141,7 +160,9 @@ public final class HSSFEvaluationWorkbook implements FormulaRenderingWorkbook, E
 		int ix = namePtg.getIndex();
 		return new Name(_iBook.getNameRecord(ix), ix);
 	}
-	public Ptg[] getFormulaTokens(EvaluationCell evalCell) {
+	
+	@SuppressWarnings("unused")
+    public Ptg[] getFormulaTokens(EvaluationCell evalCell) {
 		HSSFCell cell = ((HSSFEvaluationCell)evalCell).getHSSFCell();
 		if (false) {
 			// re-parsing the formula text also works, but is a waste of time
@@ -159,6 +180,7 @@ public final class HSSFEvaluationWorkbook implements FormulaRenderingWorkbook, E
 		FormulaRecordAggregate fra = (FormulaRecordAggregate) cell.getCellValueRecord();
 		return fra.getFormulaTokens();
 	}
+	
     public UDFFinder getUDFFinder(){
         return _uBook.getUDFFinder();
     }
diff --git a/src/java/org/apache/poi/ss/formula/EvaluationWorkbook.java b/src/java/org/apache/poi/ss/formula/EvaluationWorkbook.java
index 49f4598f5a..ca87e313a3 100644
--- a/src/java/org/apache/poi/ss/formula/EvaluationWorkbook.java
+++ b/src/java/org/apache/poi/ss/formula/EvaluationWorkbook.java
@@ -44,10 +44,21 @@ public interface EvaluationWorkbook {
 	EvaluationSheet getSheet(int sheetIndex);
 
 	/**
-	 * @return <code>null</code> if externSheetIndex refers to a sheet inside the current workbook
+	 * HSSF Only - fetch the external-style sheet details
+	 * <p>Return will have no workbook set if it's actually in our own workbook</p>
 	 */
 	ExternalSheet getExternalSheet(int externSheetIndex);
+	/**
+	 * XSSF Only - fetch the external-style sheet details
+     * <p>Return will have no workbook set if it's actually in our own workbook</p>
+	 */
+	ExternalSheet getExternalSheet(String sheetName, int externalWorkbookNumber);
+	/**
+	 * HSSF Only - convert an external sheet index to an internal sheet index,
+	 *  for an external-style reference to one of this workbook's own sheets 
+	 */
 	int convertFromExternSheetIndex(int externSheetIndex);
+	
 	ExternalName getExternalName(int externSheetIndex, int externNameIndex);
 	EvaluationName getName(NamePtg namePtg);
     EvaluationName getName(String name, int sheetIndex);
diff --git a/src/java/org/apache/poi/ss/formula/OperationEvaluationContext.java b/src/java/org/apache/poi/ss/formula/OperationEvaluationContext.java
index 6bf3ed6e32..aad61c5905 100644
--- a/src/java/org/apache/poi/ss/formula/OperationEvaluationContext.java
+++ b/src/java/org/apache/poi/ss/formula/OperationEvaluationContext.java
@@ -17,16 +17,21 @@
 
 package org.apache.poi.ss.formula;
 
-import org.apache.poi.ss.formula.ptg.Area3DPtg;
-import org.apache.poi.ss.formula.ptg.NameXPtg;
-import org.apache.poi.ss.formula.ptg.Ptg;
-import org.apache.poi.ss.formula.ptg.Ref3DPtg;
-import org.apache.poi.ss.formula.eval.*;
-import org.apache.poi.ss.formula.functions.FreeRefFunction;
 import org.apache.poi.ss.SpreadsheetVersion;
 import org.apache.poi.ss.formula.CollaboratingWorkbooksEnvironment.WorkbookNotFoundException;
 import org.apache.poi.ss.formula.EvaluationWorkbook.ExternalName;
 import org.apache.poi.ss.formula.EvaluationWorkbook.ExternalSheet;
+import org.apache.poi.ss.formula.eval.AreaEval;
+import org.apache.poi.ss.formula.eval.ErrorEval;
+import org.apache.poi.ss.formula.eval.NameXEval;
+import org.apache.poi.ss.formula.eval.RefEval;
+import org.apache.poi.ss.formula.eval.ValueEval;
+import org.apache.poi.ss.formula.functions.FreeRefFunction;
+import org.apache.poi.ss.formula.ptg.Area3DPtg;
+import org.apache.poi.ss.formula.ptg.NameXPtg;
+import org.apache.poi.ss.formula.ptg.Ptg;
+import org.apache.poi.ss.formula.ptg.Ref3DPtg;
+import org.apache.poi.ss.formula.ptg.Ref3DPxg;
 import org.apache.poi.ss.util.CellReference;
 import org.apache.poi.ss.util.CellReference.NameType;
 
@@ -70,13 +75,20 @@ public final class OperationEvaluationContext {
 	SheetRefEvaluator createExternSheetRefEvaluator(ExternSheetReferenceToken ptg) {
 		return createExternSheetRefEvaluator(ptg.getExternSheetIndex());
 	}
+    SheetRefEvaluator createExternSheetRefEvaluator(String sheetName, int externalWorkbookNumber) {
+        ExternalSheet externalSheet = _workbook.getExternalSheet(sheetName, externalWorkbookNumber);
+        return createExternSheetRefEvaluator(externalSheet);
+    }
 	SheetRefEvaluator createExternSheetRefEvaluator(int externSheetIndex) {
 		ExternalSheet externalSheet = _workbook.getExternalSheet(externSheetIndex);
+        return createExternSheetRefEvaluator(externalSheet);
+	}
+    SheetRefEvaluator createExternSheetRefEvaluator(ExternalSheet externalSheet) {
 		WorkbookEvaluator targetEvaluator;
 		int otherSheetIndex;
-		if (externalSheet == null) {
+		if (externalSheet == null || externalSheet.getWorkbookName() == null) {
 			// sheet is in same workbook
-			otherSheetIndex = _workbook.convertFromExternSheetIndex(externSheetIndex);
+			otherSheetIndex = _workbook.getSheetIndex(externalSheet.getSheetName());
 			targetEvaluator = _bookEvaluator;
 		} else {
 			// look up sheet by name from external workbook
@@ -259,10 +271,14 @@ public final class OperationEvaluationContext {
 		SheetRefEvaluator sre = getRefEvaluatorForCurrentSheet();
 		return new LazyRefEval(rowIndex, columnIndex, sre);
 	}
-	public ValueEval getRef3DEval(int rowIndex, int columnIndex, int extSheetIndex) {
-		SheetRefEvaluator sre = createExternSheetRefEvaluator(extSheetIndex);
-		return new LazyRefEval(rowIndex, columnIndex, sre);
+	public ValueEval getRef3DEval(Ref3DPtg rptg) {
+		SheetRefEvaluator sre = createExternSheetRefEvaluator(rptg.getExternSheetIndex());
+		return new LazyRefEval(rptg.getRow(), rptg.getColumn(), sre);
 	}
+    public ValueEval getRef3DEval(Ref3DPxg rptg) {
+        SheetRefEvaluator sre = createExternSheetRefEvaluator(rptg.getSheetName(), rptg.getExternalWorkbookNumber());
+        return new LazyRefEval(rptg.getRow(), rptg.getColumn(), sre);
+    }
 	public ValueEval getAreaEval(int firstRowIndex, int firstColumnIndex,
 			int lastRowIndex, int lastColumnIndex) {
 		SheetRefEvaluator sre = getRefEvaluatorForCurrentSheet();
diff --git a/src/java/org/apache/poi/ss/formula/SheetRefEvaluator.java b/src/java/org/apache/poi/ss/formula/SheetRefEvaluator.java
index 1746690050..7452d5ab58 100644
--- a/src/java/org/apache/poi/ss/formula/SheetRefEvaluator.java
+++ b/src/java/org/apache/poi/ss/formula/SheetRefEvaluator.java
@@ -28,7 +28,6 @@ import org.apache.poi.ss.usermodel.Cell;
  * @author Josh Micich
  */
 final class SheetRefEvaluator {
-
 	private final WorkbookEvaluator _bookEvaluator;
 	private final EvaluationTracker _tracker;
 	private final int _sheetIndex;
diff --git a/src/java/org/apache/poi/ss/formula/WorkbookEvaluator.java b/src/java/org/apache/poi/ss/formula/WorkbookEvaluator.java
index 3d583138cd..3daa8714cc 100644
--- a/src/java/org/apache/poi/ss/formula/WorkbookEvaluator.java
+++ b/src/java/org/apache/poi/ss/formula/WorkbookEvaluator.java
@@ -673,12 +673,10 @@ public final class WorkbookEvaluator {
 				return ErrorEval.REF_INVALID;
 		}
 		if (ptg instanceof Ref3DPtg) {
-			Ref3DPtg rptg = (Ref3DPtg) ptg;
-			return ec.getRef3DEval(rptg.getRow(), rptg.getColumn(), rptg.getExternSheetIndex());
+			return ec.getRef3DEval((Ref3DPtg)ptg);
 		}
 		if (ptg instanceof Ref3DPxg) {
-            Ref3DPtg rptg = (Ref3DPtg) ptg;
-            // TODO Return the right eval, should be easy as we already know the sheet details
+            return ec.getRef3DEval((Ref3DPxg)ptg);
 		}
 		if (ptg instanceof Area3DPtg) {
 			Area3DPtg aptg = (Area3DPtg) ptg;
diff --git a/src/java/org/apache/poi/ss/formula/eval/forked/ForkedEvaluationWorkbook.java b/src/java/org/apache/poi/ss/formula/eval/forked/ForkedEvaluationWorkbook.java
index 28aacc215e..442b748593 100644
--- a/src/java/org/apache/poi/ss/formula/eval/forked/ForkedEvaluationWorkbook.java
+++ b/src/java/org/apache/poi/ss/formula/eval/forked/ForkedEvaluationWorkbook.java
@@ -20,13 +20,13 @@ package org.apache.poi.ss.formula.eval.forked;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.apache.poi.ss.formula.ptg.NamePtg;
-import org.apache.poi.ss.formula.ptg.NameXPtg;
-import org.apache.poi.ss.formula.ptg.Ptg;
 import org.apache.poi.ss.formula.EvaluationCell;
 import org.apache.poi.ss.formula.EvaluationName;
 import org.apache.poi.ss.formula.EvaluationSheet;
 import org.apache.poi.ss.formula.EvaluationWorkbook;
+import org.apache.poi.ss.formula.ptg.NamePtg;
+import org.apache.poi.ss.formula.ptg.NameXPtg;
+import org.apache.poi.ss.formula.ptg.Ptg;
 import org.apache.poi.ss.formula.udf.UDFFinder;
 import org.apache.poi.ss.usermodel.Workbook;
 
@@ -90,8 +90,11 @@ final class ForkedEvaluationWorkbook implements EvaluationWorkbook {
 	public ExternalSheet getExternalSheet(int externSheetIndex) {
 		return _masterBook.getExternalSheet(externSheetIndex);
 	}
+	public ExternalSheet getExternalSheet(String sheetName, int externalWorkbookNumber) {
+        return _masterBook.getExternalSheet(sheetName, externalWorkbookNumber);
+    }
 
-	public Ptg[] getFormulaTokens(EvaluationCell cell) {
+    public Ptg[] getFormulaTokens(EvaluationCell cell) {
 		if (cell instanceof ForkedEvaluationCell) {
 			// doesn't happen yet because formulas cannot be modified from the master workbook
 			throw new RuntimeException("Updated formulas not supported yet");
diff --git a/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFEvaluationWorkbook.java b/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFEvaluationWorkbook.java
index 5a4bfa534b..5f326b6ad7 100644
--- a/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFEvaluationWorkbook.java
+++ b/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFEvaluationWorkbook.java
@@ -37,6 +37,7 @@ import org.apache.poi.ss.formula.udf.IndexedUDFFinder;
 import org.apache.poi.ss.formula.udf.UDFFinder;
 import org.apache.poi.ss.util.AreaReference;
 import org.apache.poi.ss.util.CellReference;
+import org.apache.poi.xssf.model.ExternalLinksTable;
 import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTDefinedName;
 
 /**
@@ -63,7 +64,8 @@ public final class XSSFEvaluationWorkbook implements FormulaRenderingWorkbook, E
 		return externSheetIndex;
 	}
 	/**
-	 * @return the sheet index of the sheet with the given external index.
+	 * XSSF doesn't use external sheet indexes, so when asked treat
+	 * it just as a local index
 	 */
 	public int convertFromExternSheetIndex(int externSheetIndex) {
 		return externSheetIndex;
@@ -175,10 +177,21 @@ public final class XSSFEvaluationWorkbook implements FormulaRenderingWorkbook, E
 	}
 
 	public ExternalSheet getExternalSheet(int externSheetIndex) {
-		// TODO Auto-generated method stub
-		return null;
+	    throw new IllegalStateException("HSSF-style external references are not supported for XSSF");
 	}
-	public int getExternalSheetIndex(String workbookName, String sheetName) {
+	public ExternalSheet getExternalSheet(String sheetName, int externalWorkbookNumber) {
+	    if (externalWorkbookNumber > 0) {
+	        // External reference - reference is 1 based, link table is 0 based
+	        int linkNumber = externalWorkbookNumber - 1;
+	        ExternalLinksTable linkTable = _uBook.getExternalLinksTable().get(linkNumber);
+	        return new ExternalSheet(linkTable.getLinkedFileName(), sheetName);
+	    } else {
+	        // Internal reference
+	        return new ExternalSheet(null, sheetName);
+	    }
+    }
+
+    public int getExternalSheetIndex(String workbookName, String sheetName) {
 		throw new RuntimeException("not implemented yet");
 	}
 	public int getSheetIndex(String sheetName) {