Hi Dave,
Thanks for your reply. For the history of this regiment there is this one:
Vereinigung des ehem. R.-Inf.-Regt. 88 Hanau: "Regimentsgeschichte des Reserve-Infanterie- Regiments 88", Hanau 1932.
and another more contemporary book:
Jens Arndt, Das Hanauer Reserve-Infanterie-Regiments Nr.88 im Weltkrieg 1914-18, Hanau 1999, (Selbstverlag: archivum militares), 144 Seiten.
but I can find no trace of either.
with kind regards
Joel