“…There exist two versions of spectral reciprocities: GL 4 × GL 2 GL 4 × GL 2 reciprocity and GL 2 × GL 2 GL 3 × GL 2 reciprocity. The former one involves work of Andersen-Kıral [1], Blomer-Li-Miller [12], Blomer-Khan [10,11], Humphries-Khan [32], Kuznetsov [45], Nunes [57], and Zacharias [69]. The latter involves work of Blomer et al [9], Nelson [56], Petrow [60], Petrow-Young [61,62], Wu [66], and Young [67].…”