Recently G. Alessandrini - V. Nesi and Kalaj generalized a classical result of H. Kneser (RKCTheorem). Using a new approach we get some new results related to RKC-Theorem and harmonic quasiconformal (HQC) mappings. We also review some results concerning bi-Lipschitz property for HQC-mappings between Lyapunov domains and related results in planar case using some novelty.