New York, NY: Bell Telephone Laboratories 1949. Later printing. 1-12 pages. 8 1/2 x 11 inches. Publisher's printed grey, blue and black wrappers. 5 hole punched at the spine as issued. Ex-library stamp on front cover dated Aug 11, 1949. Otherwise unmarked. Bell Telephone System Technical Publications, Monograph # B-1644..... More