Referee's report by William George Penney, on a paper 'A modified method of antisymmetrized molecular orbitals. II. The oxygen and ethelene molecules' by W Moffitt Sectional committee: Physics Paper reference code: A61 Recommends the paper should be published by the Royal Society. Penney remarks on the difficulty he has had with this paper, and suggests if he were writing it he would have put Part I and II together in half the space. Additional comments on a separate typescript page, discussing whether Penney has properly grasped Moffitt's argument on the oxygen molecule. [Published in Proceedings A, 1951]. Date received not given. 19 April 1951