@article{MAN_1973__201_162395,
     author = {Marston Morse},
     title = {Singular {Quadratic} {Functionals.}},
     journal = {Mathematische Annalen},
     pages = {315--340},
     publisher = {mathdoc},
     volume = {201},
     year = {1973},
     zbl = {0237.49013},
     url = {http://geodesic.mathdoc.fr/item/MAN_1973__201_162395/}
}