Villadsen, J & Michelsen, M.L Solution of differential equation models by polynomial approximation J. Villadsen & M.L. Michelsen - Englewood Cliffs Prentice-Hall 1978 - xv 446 - Prentice-hall international series in the physical & chemic . ISBN: 0138222053 Dewey Class. No.: 11.06 / VILL