"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.
There is a book"Gulashkanoe The German Field Kitchen in WW II and Reenaction" Scott L Thompson which deals with WW II but has a little info on WW I and things that would be applicable, Includes recipes ect.