1. Benilov, E. S., & Pelinovsky, E. N. 1989, in Res. Rep. in Phys., Nonlinear Waves in Active Media (Springer, Berlin)
2. Blanch, G. 1972, Mathieu's functions, in Handbook of mathematical functions, ed. M. Abramowitz, & I. A. Stegun (London, Dover), 721
3. Probing solar convection
4. Christensen-Dalsgaard, J. 1998, Lecture notes on stellar oscillations, fourth edition, Aarhus Univ. (http://www.obs.aau.dk/~jcd/oscilnotes/)