Use of the chemical potential for a limited number of fermions with a degenerate groundstate L. F. Lemmens, F. Brosens and J. T. Devreese Eur. Phys. J. B, 32 2 (2003) 195-202 Published online: 01 April 2003 DOI: 10.1140/epjb/e2003-00089-3