Reddit reviews Antique American Switchblades: Identification & Value Guide

I would start with a couple good illustrated books on the subject. Many States are very gradually getting rid of those laws, Texas, for instance, recently legalized them, getting rid of some other knife laws at the same time that dated back to the reconstruction era and were equal parts Southerners not wanting freedmen carrying knives, and carpet baggers not wanting the southerners carrying knives.

I found this one and this one to be interesting and a good starting point.