April 25, 1958
Dear Dr. Lederberg,
Thank you for your letter dated April 22.  I should be very glad to give a lecture in Madison.  You suggested my recent work on transduction of colicinogeny by phage as a topic.  I think I have not yet enough data to give a lecture only on that topic and I should prefer a more general subject such as "Colicuis[?] and colicinogenic factors" in which I can of course give some information on transduction of colicinogeny by phage.
I am not coming by plane but I am traveling by car.  I expect to stay overnight in Chicago and to arrive in the late morning or early afternoon in Madison on June 9th.
Yours sincerely,
P. FREDERICQ