1. Fourth partial report on Project no. 37 -- study of errors in field artillery practice: subject: an analysis of the sources of error in the use of the aiming circle and development of an improved instrument Author(s): Hatch, Theodore F., authorBrackett, Frederick S. (Frederick Sumner), 1896-1988, authorHorvath, Steven M., author Publication: Fort Knox, Kentucky : Armored Medical Research Laboratory, 28 March 1945 Subject(s): Military Personnel -- educationWeaponsEquipment and SuppliesUnited States