@article{GDZPPN00203591X,
title = {A comparative study of functional equations characterising sine and cosine.},
journal = {Aequationes mathematicae},
volume = {30},
year = {1986},
pages = {26-33},
zbl = {0607.39004},
url = {http://dml.mathdoc.fr/item/GDZPPN00203591X}
}
Vasudeva, H.L.; Parnami, J.C. A comparative study of functional equations characterising sine and cosine.. Aequationes mathematicae, Tome 30 (1986) pp. 26-33. http://gdmltest.u-ga.fr/item/GDZPPN00203591X/