Two more relatively unknown heroes of the American Revolution, Burgin and Higday

The "Secret Six" book reviewed below briefly mentions Elizabeth Burgin and George Higday.  Two more heroes of the American Revolution who deserve a book about their contributions to the war effort  (if there isn't one already).
Elizabeth Burgin, may have been the female spy of the "Secret Six."
George Higday, another spy, who also assisted Burgin in helping free British captives from British prison ships in NY harbor.