The intense laser-atom physics becomes hot today. There is a famous interesting phenomenon: High-order harmonic generation (HHG). Lots of works are on the single atom response in the strong field approximation. Some of them obtain the spectrum by solving the Schrödinger equation. Then they say their results agree well with the experimental ones. But in other groups, they also calculate the propagation of the generated harmonics in the medium, because the harmonics we obtain in the experiment come from lots of atoms interacting with intense laser field. Now I have a question: the spectrum obtained by solving the Schrödinger equation really agrees well with today’s experiments?