I couldn't find a thread on this agency, so here's a new one.
This is what I've been able to find out so far:
-Elaine Markson and Geri Thoma show up as AAR members, but the other two don't yet.
-I cannot find a Publisher's Marketplace page for the agency, or any website at all.
-at P&E, I found Elizabeth Sheinkman has a $, Julia Kenny is not listed at all, Geri Thoma has a $ and the agency as a whole has both a $ and the "Recommended" rating.
-A B&N review taken from Publishers Weekly says: "Agent, Geri Thoma at the Elaine Markson Agency."
-Dear Author's relisting of publishing deals states Elaine Markson is Carolyn Turgeon's agent
-This states: "[Alice] Hoffman has been represented by Elaine Markson of the Elaine Markson Agency for the past twenty-five years."
-A blog post by literary agent John Ware, in which he claims he wouldn't take on any writer who had left Elaine Markson.
-This states that Lisa Unger is Elaine Markson's client, plus google searches bring up a whole bunch of other Publisher's Lunch deals for the agency that have been posted on blogs, such as this, this and this.