@article{GDZPPN002035405,
title = {Representation formulas for cosine and sine functions of operators.},
journal = {Aequationes mathematicae},
volume = {28},
year = {1985},
pages = {162-171},
zbl = {0591.47028},
url = {http://dml.mathdoc.fr/item/GDZPPN002035405}
}
Lee, Chun-San; Shaw, Sen-Yen. Representation formulas for cosine and sine functions of operators.. Aequationes mathematicae, Tome 28 (1985) pp. 162-171. http://gdmltest.u-ga.fr/item/GDZPPN002035405/