Berger-Levrault Publishing House was founded in 1676 and is specialized in official texts. Several books and booklets printed for French Army were published by Berger-Levrault. Here’s one example: a 112-page book for officers, NCOs and soldiers who were in machine gun sections. The book is presented in a very didactic way, with simple questions and answers.
Moreover, 47 figures present all the secrets of French (and foreign) machine gun and their accessories. Look at the page dedicated to the way to transport machine guns on mules!