[1] Holtz's blog Stripper's Guide posts such regular series as "News of Yore" (including news items from back issues of Editor & Publisher), "Obscurity of the Day" (little-known strips) and a series on George Herriman.
One such obscurity discussed by Holtz is The Captain's Gig, a little-known strip by Virgil Partch; it ran as a daily and Sunday from 1977 to 1979.
[2] Maynard Frank Wolfe (Rube Goldberg Inventions) praised Holtz as "the extraordinary collector conservator computer wizard and historian of cartoon art.
"[3] Holtz is also a contributor to NBM's Forever Nuts: Classic Screwball Strips series, writing biographical introductions for the volumes on Frederick Opper and Bud Fisher, and creating annotations for Bringing Up Father and other strips reprinted in this series.
[4] His 600-page American Newspaper Comics: An Encyclopedic Reference Guide (ISBN 978-0-472-11756-7), previously available as a subscription CD service, was published by the University of Michigan Press in 2012.