"It is a laudable effort by Hettema to select, introduce and translate a well chosen set of papers by pioneers in the field from the original German into English and to make them available to a wider readership ?" Int. J. Quantum Chemistry, 2000 "It will have a lasting value for theoretical chemists and science historians." Structural Chemistry, 2000 "? is a finely produced, useful, and highly thought-provoking book." Physics Today, 2001