URL https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Shockwave_pattern_around_a_T-38C_observed_with_Background-Oriented_Schlieren_photography_(1).jpg/440px-Shockwave_pattern_around_a_T-38C_observed_with_Background-Oriented_Schlieren_photography_(1).jpg
URL2https://ja.wikipedia.org/wiki/超音速
