@article{10_4153_CJM_1969_143_4,
     author = {Stewart, James},
     title = {Unbounded {Positive} {Definite} {Functions}},
     journal = {Canadian journal of mathematics},
     pages = {1309--1318},
     year = {1969},
     volume = {21},
     number = {1},
     doi = {10.4153/CJM-1969-143-4},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1969-143-4/}
}