@article{10_4153_CMB_1969_035_1,
     author = {Haruki, Hiroshi},
     title = {On {Two} {Functional} {Equations} for the {Trigonometric} {Functions}},
     journal = {Canadian mathematical bulletin},
     pages = {281--286},
     year = {1969},
     volume = {12},
     number = {3},
     doi = {10.4153/CMB-1969-035-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1969-035-1/}
}