J. Barkley Rosser and Lowell Schoenfeld, Approximate formulas for some functions of prime numbers, Ill. Journ. Math. 6 (1962) 64-94.

(A scan of some key pages from an ancient annotated photocopy.)

Pages

64, 65, 66, 67, 68, 69, 70, 71, 72, 94.