Most of the information is from The Top Ten by Bob Gilbert and Gary Theroux (New York: Fireside, 1982), The New Rolling Stone Encyclopedia of Rock & Roll ed. by Patricia Romanowski, Holly George-Warren and Jon Pareles (New York: Fireside, 1995), and The Billboard Book of Number One Hits by Fred Bronson (New York: Billboard Publications, 1988). Rankings were compiled by Gary Theroux and Bob Gilbert through an analysis of national trade chart activity, major market radio air play, industry sales figures, and music licensing tally reports during the seventies.