On Joshua Lederberg's "Profiles in Science" NLM website, searching for "Esther Zimmer" returns the following PDF file. "EML" is mentioned on page 3, "Esther Zimmer" is mentioned on page 5.
Click to view PDF file "Joshua Lederberg Reminisces on work and life 1946-1947", 1988.
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:
bbgknx.
http://profiles.NLM.NIH.gov/BB/