Abel-like differential equations with a unique limit cycle

For the family of scalar Abel-like equations x′=A(t)xn+bB(t)xm, where A(t)=∑l=1kalsinil(t)cosjl(t), B(t)=sinib(t)cosib(t), al,b∈R, n,m,k,il,jl,ib,jb∈Z+, n,m≥2, and k≥1, we characterize the existence of non-trivial limit cycles (periodic solutions that are isolated in the set of periodic solutions different from the trivial x(t)≡0) in terms of n,m,k,il,jl,ib,jb.