The Bull's Hour (alternatively: The Ox Hour) (Russian: Час Быка, Tcha's Byka' ) is a social science fiction novel written by Russian author and paleontologist Ivan Yefremov in 1968. It was banned in the Soviet Union six months after its publication and attempted to be taken out from all the libraries and bookshops throughout the country  when it was realized by the authorities to contain a sharp criticism of the current state of affairs in the USSR though pretending to be critical of Chinese brand of political communist system.
Впрочем, русская википедия с такой точкой зрения не согласна.
BTW, книги Ефремова - из самых ярких моих тинейджерских впечатлений. Подозреваю что избыток в них скрытых (да и явных) sexual themes - одна из причин :)