1. Hsu T.T.C., Torsion of structural plain concrete rectangular sections, Journal of American concrete Institute, Detroit, 1968, Special Publication SP 18, PP 203–238.
2. Collins M.P., Walsh P.F., Archer F.E., Hall A.S., Ultimate strength of reinforced concrete beams subjected to combined torsion and bending, Torsion of structural concrete, SP-18, American concrete institute, Detroit, 1968, pp.307–336.
3. Lampert and Thurlimann, B. “Torsion tests on reinforced concrete beams.” Bericht No. 6506-2, Institute of Baustatik (ETH), Zurich, June 1968 (in German).
4. A theoretical investigation of ultimate torque as calculated by truss theory and by the Russian ultimate equilibrium method