The best available answer to this question is provided in the 16 page document [NY Genealogical and Biographical Record ][1] , that describes the Cowen sisters introduction and involvement with genealogical research.

 That article leads to [American Ancestors - the legacy of Gertrude Audrey Barber][2], that article details the many works and points to the NY State Archives for 150 of her collected works. 




  [1]: http://genealogicalforensics.com/Genealogical_Forensics/Publications_files/Part%201.pdf
  [2]: https://www.americanancestors.org/Browse/articles?searchby=country&subquery=New%20York&id=147