The Wolfen

No Wolfen-specific book-club record surfaced in the sources consulted, but the standard tells for US hardcovers of this period apply and should be checked: a blind stamp (dot, circle or square) impressed into the rear board near the spine, a jacket with no price at the front flap, thinner paper and a smaller trim size, and — for Book-of-the-Month copies — a code printed sideways at the foot of the last page inside the endpaper. A Morrow book-club printing will not carry the number line at all, which settles it against the trade first.