The history of the Wabash was the subject matter of The Railway and Locomotive Historical Society bulletin #133 published in 1975. The treatise by William Swartz is complete within the cofines of the medium in which he writes. I believe this is out of print but still in copyright. Contacting the society (I don't have its contact information) may produce a copy. The North Missouri Railroad a predecessor to the St. Louis, KC and Northern which became part of the Wabash in 1879 is mentioned in the text. :thumbs_up:
A source I've seen have OOP R&LHS publications, is Railpub.com. Folks could try there for earlier issues such as this one. Boxcab E50
Unfortunately they don't show in their catalog that they have this one. But they do have a lot of stuff that would be of interested to just about everyone. Worth checking them out.