The Gherardi Davis NY30 history is called "History of the New York Yacht Club Thirty Foot Class." It's not a book and for this reason not listed in Howland or Toy. It is a typewritten manuscript with a few photographs and four plans. I guess the only copy is at NYYC.
There are two good histories of the NY30s. One was published in the January 1925 issue of Yachting by Seabury Lawrence, "The New York Thirties. An Interesting Sketch of America's Most Famous One-Design Class", the other in 1928 by Edwin Schoettle as a chapter "The New York Thirties" in his book "Sailing Craft." Both contain very detailed provenance histories up to the respective dates of publication.