Given a fixed Hilbert modular form, we consider a family of linear maps between the spaces of Hilbert cusp forms by using the Rankin-Cohen brackets and then we compute the adjoint maps of these linear maps with respect to the Petersson scalar product. The Fourier coefficients of the Hilbert cusp forms constructed using this method involve special values of certain Dirichlet series of Rankin-Selberg type associated to Hilbert cusp forms.
"Rankin-Cohen Brackets on Hilbert Modular forms and Special values of certain Dirichlet series." Funct. Approx. Comment. Math. 58 (2) 257 - 268, June 2018. https://doi.org/10.7169/facm/1703