When parsing formula SUM('a b:c d'!F9), FormulaParser does not recognize the second sheet from multi-sheet reference 'a b:c d'!F9. Instead, it creates an org.apache.poi.ss.formula.ptg.Ref3DPxg [sheet=a b:c d ! F9] token with firstSheetName = a b:c d and lastSheetName = null