Hi, If you contact Rovela Erker she has quite a lot on the Erker family but I don't know if their information has been put in book form or if it has been published. If you find out will you please let me know, I would buy one for sure. Thank you for contacting you. My mother Anna Hilger Schwind's mother was Frances Louise Erker but they gave her the nick name "Fannie" She hated it but her cousins who was resented her gave it to her. She was a person who did not say a lot but when she did it was in a few words, and such wisdom she had. I loved he a lot. She married Herman Joseph Hilger, his father was Mathew Joseph Hilger.