I have an old copy of Robinson Crusoe and A Journal of the Plague Year, published by the Book League of America. On what I would expect to be the copyright page in a modern edition, there is only the abbreviation "CL", followed by "printed in the United States of America."
That's basically the extent of the publishing information. Defoe is on the spine, but not the title page; that just has the title as I gave it and the publisher as "The Book League of America, New York."
The two things I've found on the internet is a suggestion that the CL indicates which printing it is (but this book league really produced 150 printings of this book?) and a Harper and Brothers two letter code to indicate month and year of publication. I don't really like that one either.
Is anyone around here familiar with that particular note, CL?
The Book-League of America was a subscription-based book club founded in 1930; subscribers got 12 new books and 12 reprinted classics a year, although this began to decline as the club ran on. Robinson Crusoe was their 150th entry; hence the CL - the dustjacket should have "150" on the spine, if the dustjacket is still intact.
More generally speaking, Robinson Crusoe was first published in 1719; by the 1930s it was long in the public domain by US copyright law. This was one of the advantages of printing new editions of "classics," since you didn't have to pay a writer and there were seldom any royalties to deal with.