bobines de Helmholtz
1989 / Helmholtz coils revisited / Edward M. Purcell / American Journal of Physics 57 (1989) p. 18 [doi]
1996 / An elementary derivation of the midplane magnetic field inside a pair of Helmholtz coils / Richard C. Calhoun / American Journal of Physics 64 (1996) p. 1399 [doi]