Based on their theory, Leonhardt ascribed the Minkowski and Abraham formulas to the wave-particle duality of light: Minkowski momentum is a wave-characteristics momentum, deduced from the combination of de-Broglieʼs relation with Einstein's light-quantum theory; Abraham momentum is a particle-characteristics momentum, deduced from the combination of Newton's law with Einstein's energy-mass equivalence formula. In his reasoning, Leonhardt implicitly used a plane-wave model, where a plane wave propagates in a lossless, non-conducting, uniform medium so that the wave phase velocity and the photon moving velocity are both equal to "c/n". However this assignment of wave-particle duality is questioned by the result in a recent study, which claims that both the Minkowski and Abraham formulas can be directly obtained only from Einstein's light-quantum theory (applied to the plane wave), without any need to invoke de-Broglieʼs relation, Newton's law, and Einstein's energy-mass equivalence formula.