1.
Lino J, de Farias A, Araújo N. Aspects of the Schwinger Variational Principle Formulation. Trends Comput. Appl. Math. [Internet]. 2000 Jun. 1 [cited 2024 Dec. 18];1(1):175-8. Available from: https://tcam.sbmac.org.br/tema/article/view/505