was established as a co-operative venture between the and (RKP) in the 1950s to produce a series of major contributions across the social sciences. This volume is part of a 2001 reissue of a selection of those important works which have since gone out of print, or are difficult to locate. Published by 112 volumes in total are being brought together under the name . Reproduced here in facsimile, this volume was originally published in 1956 and is available individually. The collection is also available in a number of themed mini-sets of between 5 and 13 volumes, or as a complete collection.