Annibal Parracho Sant'Anna Inder Jeet Taneja Trigonometric entropies, Jensen difference divergence measures, and error bounds. 145-156 1985 35 Inf. Sci. 2 http://dx.doi.org/10.1016/0020-0255(85)90046-5 db/journals/isci/isci35.html#SantannaT85