Are these Cut-Outs from a Book or Some Type of Premium?

[leftygrove10]

I picked up some pictures recently of Lefty Grove, Walter Johnson, Eddie Plank, Joe McGinnity, Burleigh Grimes, Waite Hoyt, Carl Hubbell and Ed Walsh, Sr. See scans below. These pictures are on thin stock (like that of a magazine or book) and have a blank back. The pictures measure 4 1/2 by 7 3/8.

I suspect that they are from a book (Spalding Guide, perhaps?) or magazine, but picked them up just in case they happened to be some type of rare premium. Most of the pictures have nice, straight borders almost as if they were cut at the factory. Once again, they have blank backs.

Can any of you provide information on these pictures? (Some of them are really neat!) If they are from a book or magazine, please tell me which one (if possible).

Thanks for your help!