1. Chantry, G.W., and Duxbury, G.: ‘Molecular lasing systems’, Williams, Dudley, Methods of experimental physics, (Academic press, New york 1971),2, to be published
2. Chantry, G.W.: Submillimetre Spectroscopy—a Guide to the Theoretical and Experimental Physics of the Far Infra-Red, (Academic press, London 1971),2,