Steve Gerber's 1977 Howard the Duck contract
Marvel Comics' 1978 continuation of the Howard the Duck strip without Steve Gerber was the basis for his lawsuit against Marvel, which was settled out of court (the terms of the settlement remain confidential).
Howard the Duck, 1978 (Words by Marv Wolfman; Art by Alan Kupperberg)
Below, the contract between Gerber and Marvel Comics. (He signed another contract in October 1977, one that covered his comic book work, but this was the contract that most directly related to the lawsuit.)