Thanks to everyone for their advice. I appreciate all of the information, especially regarding the guide. I know it is out of date, being from 1993; however, was unaware of it being flawed. Up to this point, I had considered it to be a good resource.
Here are a few photos. One is the front cover of the book. The other two are of pages where I found info on the M101-5 cards. The author apparently believed they were issued with Sporting News backs.
I welcome any additional insight as to how trustworthy (or not) this guide may be. Collecting pre-war material is new to me and I am grateful to everyone for helping to steer me in the right direction.
Again, thank you very much.
Best Regards,
Eric