Dennis M. Ritchie ‘The Development of the C Language’ is one of those things any programmer should read soon or later, if nothing else for historic reasons.

C came into being in the years 1969-1973, in parallel with the early development of the Unix operating system; the most creative period occurred during 1972. Another spate of changes peaked between 1977 and 1979, when portability of the Unix system was being demonstrated. In the middle of this second period, the first widely available description of the language appeared: The C Programming Language, often called the `white book’ or `K&R’ [Kernighan 78].

via Chistory.