1. 1937 [1] Hamel, G., Potentialströmungen mit konstanter Geschwindigkeit. Sitzgsber. preuss. Akad. Wiss., phys.-math. Kl. 5–20.
2. 1952 [1] Prim, R. C., Steady rotational flow of ideal gases. J. Rational Mech. Anal. 1, 425–497.
3. 1953 [1] Howard, L. N., Constant Speed Flows. Doctoral dissertation. MS in the Princeton University Library.
4. 1973 [1] Marris, A. W., & J.-F. Shiau, Hamel's theorem: the three polynomial integrals. Rendiconti del Circolo Matematico di Palermo. In press.