Letter from Thomas Gold to Professor Irving Michelson, Department of Mechanical and Aerospace Engineering, Illinois Institute of Technology, Chicago, Illinois The information in Michelson's discussion of the moon's rotation is well known to workers in the field, although it represents a gap in the literature. Gold does not think it worth a separate paper but suggests that Michelson contact Professor George MacDonald at UCLA for advice. 'As an astronomer I am very sorry to have to admit that the structure of astronomical literature is patchy and often fails to contain material which is well known....We astronomers have to take the blame...' 29 July 1964