  The wave equation of low-frequency density waves in Bose-Einstein condensates
at vanishing temperature in arbitrarily anisotropic harmonic traps is separable
in elliptic coordinates, provided the condensate can be treated in the
Thomas-Fermi approximation. We present a complete solution of the mode
functions, which are polynomials of finite order, and their eigenfrequencies
which are characterized by three integer quantum numbers.
