Elementary Theory of Angular Momentum

The theory of angular momentum has long been of importance in spectroscopy, and those interested in the subject twenty-five years ago had to find their way rather painfully through highly formal textbooks and papers. The theory has lately become even more important mainly because of improvements in experimental techniques for measuring angular distributions or angular correlations in nuclear physics, and because of problems in low-temperature studies and in microwave spectroscopy involving static moments coupled to fields arising from surrounding charges.