@article{03989483,
title = {Trigonometric identities.},
journal = {International Journal of Mathematics and Mathematical Sciences},
volume = {9},
year = {1986},
pages = {705-714},
doi = {10.1155/S0161171286000844},
zbl = {0612.12008},
language = {en},
url = {http://dml.mathdoc.fr/item/03989483}
}
Baica, Malvina. Trigonometric identities.. International Journal of Mathematics and Mathematical Sciences, Tome 9 (1986) pp. 705-714. doi : 10.1155/S0161171286000844. http://gdmltest.u-ga.fr/item/03989483/