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Numerical Computation 
Numerical Computation Guide  
Numerical Mathematics in Scientific Computation (Åke Björck)
Numerical Recipes in C [Mirror] An Introduction to Multigrid Methods (A. Borzi)
Numerical Recipes in Fortran 77 [Mirror] Numerical Recipes in Fortran 90 [Mirror]
Electronic Transactions on Numerical Analysis LAPACK Users' Guide, 3rd Edition