1. W. Thomson, “On the motion of rigid sonds in a liquid circulating irrotationally through perforations in them or in any fixed solid,” Proc. R. Soc. Edinburg, No. 7, 668–674 (1872).
2. V. Volterra, “Sur la theorie des variations des latitudes,” Acta Math. 22, 201–358 (1899).
3. N. E. Zhukovskyii, “On the motion of a solid body having cavities filled with a homogeneous dropping liquid,” in Collection of Scientific Papers (Moscow, 1949), Vol. 1, pp. 31–152 [in Russian].
4. A. Gray, A Treatise on Gurostatics and Rotational Motion. Theory and Applications (Dover Publ., New York, 1959).
5. T. Levi-Civita and U. Amaldi, Lezioni di meccanica razionale (Verlag Nicola Zanichelli, Bologna, 1930), Vol. 2, Part 2.