There are on this site several questions and answers about morphophonemes and morphophonemic changes. Go to the start of the Question and Answer section. Go down about 15 lines and click on "view all answers." Then go up a couple of lines and type "morphophonem" (without the quotes) into the Keyword box. This will catch all answers that contain the words morphophoneme and morphophonemic. Then hit Search, and you can read all the questions and answers.
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