@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/