 He has written many scientific papers and seven books, of which perhaps the best known are "Coulson's Valence", an update of the famous book by Charles Coulson in 1951, and the two editions of "Methods of Molecular Quantum Mechanics", (the first edition with B. T. Sutcliffe in 1969 and the second edition alone in 1989).He wrote several chapters in the three volumes of the "Handbook of Molecular Physics and Quantum Chemistry".In 1963 he wrote "Symmetry