@article{10_4153_CJM_1978_042_3,
     author = {Faulkner, G. D. and Shonkwiler, R. W.},
     title = {Cosine {Representations} of {Abelian} {*-Semigroups} and {Generalized} {Cosine} {Operator} {Functions}},
     journal = {Canadian journal of mathematics},
     pages = {474--482},
     year = {1978},
     volume = {30},
     number = {3},
     doi = {10.4153/CJM-1978-042-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1978-042-3/}
}