DETERMINATION OF ORE CONCENTRATION IN EXPLORATION HOLES BY THE GAMMA-RAY BACKSCATTERING TECHNIQUE AND DISCUSSION.DONHOFFER DK.1969; INTERNATION. SUBCOMMISS. STRATIGR. CLASSIF. I.U.G.S. COMMISS. STRATIGR., CIRC; USA; 1969, VOL. 1968, P. 23 A 35Miscellaneous

AN AIRBORNE GAMMA-RAY SPECTROMETRY SYSTEM FOR GEOLOGICAL SURVEYING.BRISTOW Q; DONHOFFER DK.1968; TRANS. AMER. NUCL. SOC.; USA; 1968, VOL. 11, NUM. 0001Miscellaneous

AIRBORNE GAMMA-RAY SPECTROMETER EXPERIMENTS OVER THE CANADIAN SHIELD AND DISCUSSION.DARNLEY AG; BRISTOW Q; DONHOFFER DK et al.1969; INTERNATION. SUBCOMMISS. STRATIGR. CLASSIF. I.U.G.S. COMMISS. STRATIGR., CIRC; USA; 1969, VOL. 1968, P. 163 A 186Miscellaneous