“…For the case of circular and spherical domains, if r = 1, then k 2 l,m = l(l + 1). Taking x ∈ B, y ∈ Γ , then writing in polar coordinates x = ry, r ∈ (0, 1) we can define, for all l ∈ N 0 , m ∈ Z, |m| ≤ l, the following power series solutions [35,36] …”