| IBM TDB, R. A. Bielling et al, "Second Sheet Restraint", vol. 23, No. 9, Feb. 1981. |
| IBM TDB, R. A. Bielling et al, "Sheet Supply Hopper", vol. 23, No. 8, Jan. 1981. |
| IBM TDB, D. A. Deeds et al, "Envelope Gate", vol. 19, No. 3, Aug. 1976. |
| IBM TDB, K. A. Lennon et al, "Sheet Positioning Apparatus", vol. 17, No. 10, Mar. 1975. |
| IBM TDB, R. G. Hart et al, "Document Feed Interrupt", vol. 8, No. 10, Mar. 1966. |
| IBM TDB, P. Feinstein et al, "Envelope Feeding Mechanism", vol. 19, No. 10, Mar. 1977. |
| Soviet Inventions Illustrated, Sections P, Q, Week B22, issued Jul. 11, 1979, London, England. |