The Bulletin of Symbolic Logic Bibliography J. Lambek . On certain formal properties of grammars. The system F of variable types, fifteen years later. Least fixpoints of endofunctors of cartesian closed categories. On completeness and cocompleteness in an around small categories.
Lambek grammars are context free.
IEEE Computer Society Press. J. C. Shepherdson and H. E. Sturgis. Computability of recursive functions.