The Ellipsoidal Harmonics when , , and are given can be arranged in such a way that the th function has zeros between and and the remaining zeros between and (Whittaker and Watson 1990).
See also Ellipsoidal Harmonic
References
Whittaker, E. T. and Watson, G. N. A Course in Modern Analysis, 4th ed. Cambridge, England:
Cambridge University Press, pp. 560-562, 1990.