This series contains mainly professional correspondence with academic colleagues regarding research and professional activities. It documents the academic discussions and exchange of ideas between Hollander and well known international economists such as R.C.D. Black, Walter Eltis, T.W. Hutchinson, Mark Blaug, Martin Brofenbrenner, Don Patinkin, Giovani Caravale, Piero Bruchi, Maurice Daune, Ronald Meek, William Jaffe, A.P. Lerner, Hal Brauner, and R. Dorfman. Among his Canadian colleagues represented are Jack Robson, E.G. West, Scott Gordon, Harry Johnson, C.B. MacPherson, Tom Rymes, and A.M.C. Waterman.
His continued connections to his former universities are documented through his correspondence with Lord Robbins and Michio Morishima of the London School of Economics and with William Baumol and Fritz Machlup of Princeton University. Former students, academics in their own right, are also represented in the correspondence including Margaret Schabas, Evelyn Forget and Sandy Peart.
There is also extensive correspondence with Nobel Laureates Sir John Hicks documenting their collaborative research on Ricardo in the 1970s and with Paul Samuelson of MIT. Other Noble laureates represented include R.H. Coase, Kenneth Arrow, Arthur Lewis and George Stigler.