Ionization potentials, appearance potentials, and heats of formation of gaseous positive ions, by J. L. Franklin, J. G. Dillard, H. M. Rosenstock, J. T. Herron, K. Draxl, F. H. Field. National Standard Reference Data System, National Bureau Of Standards, 26, Superintendent of Documents, US Government Printing Office, Washington, D.C. 20402, 1969. 289 pp. $4.00