TOMS612 is a FORTRAN77 library which approximates the integral of a function over a triangular region.
TOMS612 is available in a FORTRAN77 version.
DUNAVANT, a FORTRAN90 library which defines Dunavant rules for quadrature on a triangle.
FEKETE, a FORTRAN90 library which defines a Fekete rule for quadrature or interpolation over a triangle.
INTLIB, a FORTRAN90 library which numerically estimates integrals in one dimension.
LYNESS_RULE, a FORTRAN90 library which returns Lyness-Jespersen quadrature rules for the triangle.
MACHINE, a FORTRAN77 library which stores the appropriate values of machine constants for a given machine.
NINTLIB, a FORTRAN90 library which numerically estimates integrals in multiple dimensions.
QUADPACK, a FORTRAN90 library which estimates integrals in one dimension.
QUADRULE, a FORTRAN90 library which defines quadrature rules on a variety of intervals with different weight functions.
STRI_QUAD, a FORTRAN90 library which can approximate the integral of a function over the surface of a sphere.
STROUD, a FORTRAN90 library which defines quadrature rules on a regions of a variety of shapes and dimensions.
TEST_NINT, a FORTRAN90 library which can be used to test N-dimensional quadrature routines.
TEST_TRI_INT, a FORTRAN90 library which can be used to test algorithms for quadrature over a triangle.
TOMS351, a FORTRAN77 library which estimates an integral using Romberg integration.
TOMS379, a FORTRAN77 library which estimates an integral.
TOMS418, a FORTRAN77 library which estimates the integral of a function with a sine or cosine factor.
TOMS424, a FORTRAN77 library which estimates the integral of a function using Clenshaw-Curtis quadrature.
TOMS468, a FORTRAN77 library which carries out the "automatic" integration of a function.
TOMS706, a FORTRAN77 library which estimates the integral of a function over a triangulated region.
WANDZURA, a FORTRAN90 library which defines Wandzura rules for quadrature on a triangle.
You can go up one level to the FORTRAN77 source codes.