@article{ASNSP_1989_4_16_4_487_0,
     author = {Clarke, Frank H. and Loewen, Philip D.},
     title = {An intermediate existence theory in the calculus of variations},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {487--526},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 16},
     number = {4},
     year = {1989},
     mrnumber = {1052732},
     zbl = {0727.49004},
     language = {en},
     url = {http://archive.numdam.org/item/ASNSP_1989_4_16_4_487_0/}
}