While the modern debate over the number of singers in Bach's vocal music stems from Joshua Rifkin's controversial 1981 paper given to the American Musicological Society, other scholars and performers have previously speculated on the number of singers Bach, and even his contemporaries Telemann and Graupner, employed. Rifkin and Andrew Parrott have both argued that one, and when necessary, two singers per part is supported by extant performing materials and the famous Entwurf of 1730. Furthermore, this practice is consistent with the practices of 17th century concertists, the tradition Bach inherited. Roots of this debate can be traced to 1886-87 when William Foster Apthrop observed that Bach used a small choir even while large symphonic choirs dominated the performance platform. As early as 1920, Arnold Schering posited that 12 singers were employed to sing based on the audition reports of 1729, the 1730 Entwurf, and iconographic evidence. His opinion influenced performers such as Charles Kennedy Scott, Wilhelm Ehmann, and Robert Shaw. As period instrument recordings proliferated, forces have generally ranged from 12-20 singers, with notable solo concertisten employed by Paul McCreesh. Many of the strong opinions exist on both sides of the debate. Examining historical evidence and all leads should be the first concern, from which contemporary performance practice will follow. A chronological bibliography of primary literature on this topic encourages readers to come to terms with the issues.