Hello Bernhard and Rick.
I think Colonel E. Schuler has in fact published at least one book. In my regiment's library I found "Infanterie im Kampf - Erfahrungen und Lehren aus Gefechtsberichten" by Oberst a. D. Emil Schuler and Oberst a. D. Hans Werner Stirius. Published in 1963 by Wehr und Wissen Verlagsgesellschaft, Darmstadt.
I hope it can be helpful to you both.
Henrik Hvilsom