1. E. M. GELBARD, “Application of Spherical Harmonies Methods to Reactor Problems,” WAPD-BT-20, Bettis Atomic Power Laboratory (1960).
2. E. M. GELBARD, “Simplified Spherical Harmonics Equations and Their Use in Shielding Problems,” WAPD-T-1182, Bettis Atomic Power Laboratory (1961).
3. E. M. GELBARD, “Applications of the Simplified Spherical Harmonics Equations in Spherical Geometry,” WAPD-TM-294, Bettis Atomic Power Laboratory (1962).