1. For an up-to-date and comprechensive of the Galilei group and its applications seeE. Inönü andE. P. Wigner:Nuovo Cimento,9, 705 (1952).
2. V. Bargmann:Ann. Math.,59, 1 (1954).
3. J.-M. Lévy-Leblond's article inGroup Theory and its Applications, edited byE. M. Loebl, Vol.2 (New York, 1971). Regarding pioneering papers on the subject, cf. ref. (1,2)E. Inönü andE. P. Wigner:Nuovo Cimento,9, 705 (1952).V. Bargmann:Ann. Math.,59, 1 (1954). as well asM. Hamermesh:Ann. of Phys.,9, 518 (1960);
4. J.-M. Lévy-Leblond:Journ. Math. Phys.,6, 1519 (1965);
5. J. Voisin:Journ. Math. Phys.,6, 1519 (1965).