One of the original references on this topic is a Handbook:Classifying the U.S. "BI-PLANE and MONO-PLANE" Slogan Cancels, by Vi Vandenbloom, published in 1979.
There is also on the APS website in their Exhibit Section an exhibit titled:The types and Uses of the International "Air-Mail Saves Time" Slogan Cancel -- 1924 to 1941.
, by David Reitsema, 2012, 98 pages, 16.4 MB
Which can be downloaded as a PDF file.
Go to URL: http://stamps.org/United-States-Exhibits
and scroll down a few exhibits.
This is a fun area to collect. I played around with it for a while many years ago.