The 'Selected Works of Chairman Mao' (毛泽东选集) was second to Quotations in terms of number of copies distributed during the Cultural Revolution. It was first produced by the central authorities in the early 1950s to educate the masses on Marxist-Leninism and 'Mao Zedong Thought', in a bid to strengthen the ideological foundations of the country. Selected Works comprises four volumes and includes important articles Mao had written in different periods of the Chinese revolution.