A Treasury of Folk Songs
This work is in the public domain in the United States because it was legally published within the United States (or the United Nations Headquarters in New York subject to Section 7 of the United States Headquarters Agreement) before 1964, and copyright was not renewed.
Works published in 1948 would have had to renew their copyright in either 1975 or 1976, i.e. at least 27 years after it was first published / registered but not later than 31 Decemberin the 28th year. As it was not renewed, it entered the public domain on 1 January 1977 .