1. WalkerAnalytical Theory of Light, Cambridge, 1904, 361et seq.
2. PockelsLehrbuch der Kristalloptik, Teubner, 1906, 336et seq.
3. SzivessyHandbuch der Physik, Springer, 1928, Kap 11, 810et seq.
4. MascartTraite d’Optique, 1889, Tome 1, 240; 1891, Tome 2, 301, 317.
5. PancharatnamProc. Ind. Acad. Sci., 1956,54 A, 247.