@incollection{MSMF_1979__60__177_0,
     author = {Toland, John F.},
     title = {On subdifferential calculus and duality in non-convex optimization},
     booktitle = {Analyse non convexe (Pau, 1977)},
     series = {M\'emoires de la Soci\'et\'e Math\'ematique de France},
     pages = {177--183},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {60},
     year = {1979},
     doi = {10.24033/msmf.269},
     mrnumber = {81m:49013},
     zbl = {0417.90088},
     url = {http://archive.numdam.org/articles/10.24033/msmf.269/}
}