In conducting recent research I have found that two other newspapers (besides Altoona Tribune) advertised the m101 Mendelsohn sets– The Okmulgee (OK) Daily Democrat and the Arkansas Democrat. I found full-page ads for Okmulgee dated April 3, 1916 and April 23, 1916. Each had drawing-ish likenesses of the actual poses used for Chapman, Wagner, Collins, Evers and Alexander, although no card numbers were shown. It also included a pic of the Napoleon Lajoie “card” but it had the hands on hips pose found in the Mendelsohn flyer and the 1915 M-Unc set. The ad offered 100 cards to anyone who could get a new four-week subscription sold and 200 cards if two such subscribers were found– they needed to fill out the coupon/form and so did the kid who found them. The two ads appear to be identical. No indication of whether the backs had anything on them.
As for the Arkansas Democrat, they offered a full page ad with the same format as the Oklahoma pair, although they added images of the Joe Jackson and Heiny Zimmerman cards on either end of the fanned-out display. Kids were required to obtain a ten-week subscriber to earn 100 cards and another of the same for the other 100 cards. After the initial ad on April 7, 1916, frequent ads ran thereafter until May 22; however, all of these were simply a quarter page or so in size and had the heading “Boys! Boys! Boys!” followed by the offer and then most of the rest as a subscription form. These subsequent ads ran on April 8, 12, 18-20, 22, 26-27, May 3-5, 13, 15-17 and finally 22. Like the Okmulgee cards, there is no indication of whether the backs had anything on them.
Given the Lajoie pose and early dates of the initial ads, these were most probably m101-5 cards being offered.
Because no one has yet found m101s with ads for either of these newspapers on the back, PLEASE BE WARY OF any that pop up from now on. There's a very strong chance that if any of these exist they are blank-backed-- heck you may already own some
I will post scans of the ads shortly.