“…The kernel formula for unitary representations of PGL 2 pRq first appears in the book of Cogdell and Piatetski-Shapiro [CPS], and has been generalized to GL 2 pRq and GL 2 pCq in [Qi5,§ §17,18]. For its applications to establishing the Kuznetsov formula and the Waldspurger formula, we refer the reader to [CPS,Qi1,BM1,CQ2,BM2,CQ1]. For the unitary case, the kernel formula is actually valid for all W φ papxqq in the Kirillov model.…”