CHARM PHOTOPRODUCTION AT 20 GEV - ABE, K; BACON, TC; BALLAM, J; BEVAN, AV; BINGHAM, HH; BRAU, JE; BRAUNE, K; BRICK, D; BUGG, WM; BUTLER, JM; CAMERON, W; CARROLL, JT; et al. (PHYSICAL REVIEW D, 1984)