As Michael Douglas

With his brother Douglas, Michael Cricthon wrote the novel Dealing Or The Berkeley-to-Boston Forty-Brick Lost-Bag Blues in 1970, under the pseudonym made by putting their two first names together. Playboy magazine published it in three installments in its December 1970, January 1971 and February 1971 issues.
It also became a film under the same title in ... yes, you guessed it: 1972.