We discuss few very recent results of works in progress (in collaboration with I. Gaiur and D. Van Straten and with V. Buchstaber and I. Gaiur) about interesting properties of multiplication generalized Bessel kernels, which include well-known Clausen and Sonin-Gegenbauer formulae of XIX century, special examples of Kontsevich discriminant loci polynomials, raised as addition laws for special two-valued formal groups (Buchshtaber-Novikov-Veselov) and period functions solving some Picard-Fuchs equations similar to Calabi–Yau and related to Landau–Ginzburg– like models.
