On Joshua Lederberg's "Profiles in Science" NLM website, searching for "Esther Zimmer" returns the following PDF file, described as mentioning "Esther Lederberg". In fact, this file displays a letter written to "Esther Zimmer". (Joshua and Esther Zimmer were not married until December 13, 1946.)
Click to view PDF file referring to "Esther Zimmer",
not "Esther M. Lederberg".
Note: the file opens in a new instance of your browser.
This specific piece of correspondence may be found on Joshua
Lederberg's NLM website, identified as with the ID:
bbagic.
http://profiles.NLM.NIH.gov/BB/