DRAFT "Heinz" Harcourt's collaborations: Over 57 varieties book, three articles and five chapters in books. Claudio Sardoni and Avi Cohen are equal third, both four times. With Claudio, I have one book and three chapters in books; with Avi, I have one article, one note, and two chapters in books 1. The rest of the chapter contains reflections on why and what I have done with others. I start by saying that my personal and working life has been greatly enriched by these joint happenings, whereby I have both made new friends and deepened already established friendships 2. My collaborators may be classified into two broad categories: first, present or past graduate students; secondly, internal or external colleagues.