  For analyzing anisotropic low relative-velocity correlation-functions and the
associated emission sources, we propose an expansion in terms of cartesian
spherical harmonics. The expansion coefficients represent angular moments of
the investigated functions. The respective coefficients for the correlation and
source are directly related to each other via one-dimensional integral
transforms. The shape features of the source may be partly read off from the
respective features of the correlation function and can be, otherwise, imaged.
