In 1983 , Gorenstein announced that the proof of the classification had been completed .
Gorenstein had been misinformed about the status of the proof of classification of quasithin groups , which had a serious gap in it .
In 1983 , Gorenstein announced that the proof of the classification had been completed , but he had been misinformed about the status of the proof of classification of quasithin groups , which had a serious gap in it .