Courant R.Hilbert D.Methods o f mathematical physics—vol IInterscience Publishers IncNew York pp 252-2571953
2.
Noble B.Applied variational methods Unpublished notes University of Wisconsin Department of Mathematics Madison January 1963
3.
Noble B.Complementary variational principle for boundary value problems I: basic principles, with an application to ordinary differential equationsMath Research Center Technical Summary Report University of Wisconsin Army Math Research Center Madison #473 November 1964
4.
Rall L.B.On complementary variational principlesJournal of Mathematical Analysis and Applications vol 14 pp 174-1841966
