Morphophonemics is another term for morphophonology.
The term apparently goes back to Hockett (1958:135) (or was made popular by him).
- "The ways in which the morphemes of a given language are variously represented by phonemic shapes can be regarded as a kind of code. This code is the morphophonemic system of the language." (Hockett 1958:135)
- Hockett, Charles F. 1958. A course in modern linguistics. New York: Macmillan.