text: public String[] getExternalBookAndSheetName(int extRefIndex) {int ebIx = _externSheetRecord.getExtbookIndexFromRefIndex(extRefIndex);SupBookRecord ebr = _externalBookBlocks[ebIx].getExternalBookRecord();if (!ebr.isExternalReferences()) {return null;}int shIx1 = _externSheetRecord.getFirstSheetIndexFromRefIndex(extRefIndex);int shIx2 = _externSheetRecord.getLastSheetIndexFromRefIndex(extRefIndex);String firstSheetName = null;String lastSheetName = null;if (shIx1 >= 0) {firstSheetName = ebr.getSheetNames()[shIx1];}if (shIx2 >= 0) {lastSheetName = ebr.getSheetNames()[shIx2];}if (shIx1 == shIx2) {return new String[]{ebr.getURL(),firstSheetName};} else {return new String[]{ebr.getURL(),firstSheetName,lastSheetName};}}