1. ASME boiler and pressure vessel code, Section III,1983
2. GOST 24755-89 (ST SEV 1639-88). Vessels and apparatuses, codes and methods of calculation on strength of reinforcement of opening. Moscow, 1989.
3. The state of stress at the perpendicular intersection of two right circular tubes;Reidelbach;Ingr-Arch,1961
4. Stress distribution at two normally intersecting cylindrical shells;Eringen;Nucl Engng Des,1965
5. Photoelastic study of the stresses near openings in pressure vessels;Taylor;Welding Res Council Bull,1966