  We report on measurements and a detailed analysis of the reversible
magnetization of superconducting NbSe2 single crystals. By comparing the
experimental data with Ginzburg Landau theory we show that superconductivity in
NbSe2 cannot be explained by an anisotropic single-band, but by a multi-band
scenario. Applying a simple two-band model reveals the basic mixed-state
parameters, which are quite different in the two bands. We identify a strongly
anisotropic band that determines the properties at high magnetic fields, and a
second almost isotropic band that dominates at low fields. Our method is well
suited for distinguishing anisotropic single-band from multi-band
superconductivity in various materials.
