Kermit Sigmon, Matlab Primer University of Florida, 1992. There is an updated version for sale.
Another useful site is Portland:Matlab Hypertext Reference
A very nice book on Matlab is:
Matlab Guide by Desmond J. Higham and Nicholas J. Higham, SIAM, 2000. xxii+283 pages, softcover, ISBN 0-89871-516-4.