The Peter Fullmer Family Organization has published three amazingly detailed books about the family of Peter and Susannah Fullmer. These books are available for purchase through Amazon.com.
Peter Fullmer and Susannah Zerfass Fullmer: Their Ancestry and Their Posterity, Volumes 1 and 2
(Volume 2 is currently out of print, but you may find it from some private sellers.)
John Solomon Fullmer: The Man and His Writings
The collection of organization newsletters from 1952 to 1991 is available to view online through FamilySearch.com. In the catalog, it is listed as follows:
Peter Fullmer family newsletters, 1952-1991, call number 929.273 F959pf
These newsletters contain updates on research that was completed by the date of publication. This collection is fully indexed and includes some information on descendants and genealogical policies not covered in the books.