Standard Aircraft Characteristics sheets describing the Boeing XB-52 as of December 1949. This was not the B-52 as it was actually built… a number of design changes were yet to come. Most notable is that the wing is much closer to the nose. The cockpit in fact extends aft beyond the leading edge of the wing root.
SAC sheets used to be produced in large numbers to describe in concise form not only the aircraft the USAF was flying, but aircraft it was hoping to fly. These sheets would be produced by the USAF or by the contractors; contractors would often produce SACs describing conceptual or preliminary designs. There does not seem to have been a central clearinghouse for them… they were produced and distributed with no readily apparent rhyme or reason.
More images and data on this design are HERE.