Python Reference Manual by Guido van Rossum, CNRI
Dive Into Python manual
(1.28 MB PDF file)
iPython manual (677 KB PDF file)
matplotlib User's Guide & Manual (9 MB PDF file)
SciPy
(Scientific Tools for Python) &
NumPy
(Numerical Python)
FiPy (Finite element Python) (2.08 MB PDF file)
User's Guide to F2PY (a python wrapper for FORTRAN)