{TAIL ~ Either a single ester} or a mixture of {HEAD ~ esters} can be used as organic acid esters 
{ TAIL ~ Either a single ester } or a mixture of { HEAD ~ esters } can be used as organic acid esters
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH