gauss quadrature

Hi,
There is an online book on FEM by Carlos Felippa of the colarado university. all 3 volumes of the book are PDF format and available online. In the introductory book of FEM in one of the chapters he has discussed in detail gaussian quadrature for triangles.

See the folowing link for the online Book

I dont think there should be any diffculty otherwise in deriving the weighting functions and integraqtion points from usual procedures.

Generally when we go for higher ordr triangluar elements the problem lies in writing the shape functions , we resort to some techniques like "silvesters scheme" to write the shape functions....and possibly the intresection of reference lines there gives u an idea of approximate gauss point locations.....for more info on this refer to book by Heubuner.
hope it helps
regards
Raj