Sidney Lau (Traditional Chinese: 劉錫祥) wrote a series of textbooks in the 1970s, for teaching western people to speak Cantonese. The textbooks were initially used for teaching western expatriates working in the Hong Kong Police Force and other government bodies. Later the texts were used as a basis for a radio teaching programme for foreigners. Traditional Chinese characters are one of two standard character sets of printed contemporary Chinese written language. ... The 1970s in its most obvious sense refers to the decade between 1970 and 1979. ... The word western is an adjective used to refer to things that are in the West. ... Standard Cantonese is a variant of Cantonese and is generally considered the prestige dialect of Cantonese. ... The Hong Kong Police Force (香港警察) (from 1969 to 1997, Royal Hong Kong Police Force (皇家香港警察) is the police force of Hong Kong Special Administrative Region of the Peoples Republic of China. ...

The introduced Lau's own romanisation system which differs from the Yale system by using superscripted numbers and symbols to indicate the word tones. The Yale Romanizations are four systems created during World War II by the United States for its soldiers. ...

Despite their age, the books are still very popular being one of the few comprehensive books teaching spoken Cantonese (as opposed to written Chinese and spoken Standard Mandarin which is significantly different). The Chinese written language consists of a writing system stretching back nearly 4000 years. ... Standard Mandarin is the official Chinese spoken language used by the Peoples Republic of China, the Republic of China on Taiwan, Malaysia and Singapore. ...