AFAIK there are no books by Mitsuo Maeda.
There has been såeculation that he was involved with production of
Defensa personal al alcance de todos By Unknown Author, San Salvador, El Salvador, Tipografía Nacional, 1913
Jiudo : uma arte de cultura physica japonesa By Unknown Author, Para-Belem Brazil Livraria Escolar 1935 17p
The first was produced in connection of Japanese troupe visiting El Salvador and after exhibition matches teaching the military at their academy. The troupe had Nishimura and Maeda with them. Most probable author is the "translator" Alberto García Dechent. On the other hand how do we define an author?
The second is even weaker as it is most probable only a translation of Japanese orginal. The authorship claim was AFAIK first done By Virgilio Stanlei but has not been confirmed. see e.g.
However it might be so that in the first one can see pictures of Maeda performing techniques. These kind of books one can find others.