@article{GDZPPN002550458,
title = {A representation formula for strongly continuous cosine families.},
journal = {Aequationes mathematicae},
volume = {20},
year = {1980},
pages = {251-256},
zbl = {0467.47037},
url = {http://dml.mathdoc.fr/item/GDZPPN002550458}
}
Webb, G.F. A representation formula for strongly continuous cosine families.. Aequationes mathematicae, Tome 20 (1980) pp. 251-256. http://gdmltest.u-ga.fr/item/GDZPPN002550458/