WHITEHEAD, A.N. & B. RUSSELL. Principia mathematica. 1950. 3 vols. 4°. Ocl w. dust-j. (Spines discold., some wear to the dust-j.). Reprint of the 1927 second edition. -- B. RUSSELL. The principles of mathematics. 1964. Ocl. -- And 1 o. by R. (5).