Johnson, Pearce (1987). "When Did They Start?"(PDF). Coffin Corner. 9 (6). Professional Football Researchers Association: 1–5. Archived from the original(PDF) on 2010-11-27.
Riffenburgh, Beau & Bob Carroll (1989). "The Birth of Pro Football"(PDF). Coffin Corner. 11 (Annual). Professional Football Researchers Association: 1–30. Archived from the original(PDF) on 2010-11-27.
PFRA Research. "Five Hundred Reasons"(PDF). Coffin Corner. Professional Football Researchers Association: 1–6. Archived from the original(PDF) on 2010-09-29.
PFRA Research. "The A's Have It"(PDF). Coffin Corner. Professional Football Researchers Association: 1–4. Archived from the original(PDF) on 2010-11-26.
Johnson, Pearce (1987). "When Did They Start?"(PDF). Coffin Corner. 9 (6). Professional Football Researchers Association: 1–5. Archived from the original(PDF) on 2010-11-27.
Riffenburgh, Beau & Bob Carroll (1989). "The Birth of Pro Football"(PDF). Coffin Corner. 11 (Annual). Professional Football Researchers Association: 1–30. Archived from the original(PDF) on 2010-11-27.
PFRA Research. "Five Hundred Reasons"(PDF). Coffin Corner. Professional Football Researchers Association: 1–6. Archived from the original(PDF) on 2010-09-29.
PFRA Research. "The A's Have It"(PDF). Coffin Corner. Professional Football Researchers Association: 1–4. Archived from the original(PDF) on 2010-11-26.