This is a former library copy, for reference. It was never checked out. It includes the 6 page errata addendum, completely intact (none of the changes have been cut & pasted). Published in 1949, it's in remarkedly good shape (very clean on the inside) for a 72 yr old reference book. The spine is darkened, likely from sitting on a shelf, since there is very little wear on the front & back covers. PM me if you have any questions or need additional pics.