Volumes 1-5 cover central and western South Asia, North America, Central and South America, Oceania, and Europe and the USSR, respectively. Each volume begins with an extensive introduction providing background information on languages of the area. This is followed by a bibliography of sources for the data. The statistical tables listing the data comprise the bulk of each volume. The editors provide an index of statistical offices and a language and country index. Explanatory material and headings throughout the volumes are in both English and French.