Oxford: Clarendon Press, 1953. Octavo. (24) pp, sewn, in grey paper covers. Yapp edges of covers have a few small nicks; small chip to head of spine; one inch split at foot of spine fold; small rubber stamped name of J.M.O. Wheatley to upper outer corner of title page; VG copy otherwise. Coulson was an English theoretical chemist who developed a molecular orbital theory and the chemical concept of partial valency, as well as a number of mathematical techniques useful to chemists and physicists. He was a Professor of Theoretical Physics at King's College, London, Professor of Mathematics at Oxford from 1952, and eventually Oxford's first Professor of Theoretical Chemistry.