This tiny gummed label, found barely attached to the inside of an old book, is just 40 millimeters by 15 millimeters.
The last number of the date looks like a 6 to me, making it 1936.
I do not believe this is related to the Bookcraft that published books for the LDS Church starting in 1942 in Salt Lake City, Utah.
I found another label like this posted on flickr with with the note: "Sorta iffy on the whole Book Trade connection. Seems to be used by students for textbooks to be returned or sold back to school."
Seven Roads' Gallery of Book Trade Labels, which is one of the definitive resources for bookseller labels, agrees that this one is a mystery. Seven Roads' page of mysteries also includes The Brown Shop, MDC Books, Nyland's Bookstore, The Sign of the Mermaid, Witch's Boy Bookstall and number of other nifty puzzlers.
If you have any insight about Bookcraft, please help out in the Comments section.