Almost all of the sources found were published by note worthy university presses and academic journals and all but one were peer reviewed. The writers of these pieces are likely professors, researchers, or scholars in this area. Check out the following sources:
Narrative in Concrete / Concrete in Narrative: Visual Poetry and Narrative Theory 2014
Illusions of simplicity A cognitive approach to visual poetry* 2010
The Poesis of Space: Prosodic Structures in Concrete Poetry 1977
Having a work published in an academic journal, or university press, gives the author a sort of perceived authority on the subject. In order to be published in these spaces, the authors usually have to be peer reviewed, which is another validation system that this work and this author is legitimate. In this context peer review does not just mean reviewed by those around you, like friends and family, but rather it is by academic professionals in this area.
Concrete Poetry? 