upward

Band spectra and related functions

Arscott F M, Periodic differential equations (Pergamon, 1964)

Mathieu functions

Meixner J, Schafke F W, Wolf G, Mathieu functions and spheroidal functions, LNM 837 (1980)

Lame functions

Maier R S, Lame polynomials, hyperelliptic reductions and Lame band structure, math-ph/0309005