search privious posts (older)....there are some books....
1) DSP using MATLAb by Ingle
2) DSP By Prokis & ...
3) Digital Filter Design using MTLAB
and some other books are also there.
and also "MATLAB help" is amazing....so decide wht do u want to do ...search it in help and then use the corresponding MATLAB function for understanding the concept...Got my point????