These books do not in fact exist outside of Chang's fictional realm, but Chang has the late author of historical novels Gao Yang "endorse" the books with commentary and annotations, and refers to the "possible mystery" surrounding them.
《奇門遁甲術概要》趙太初 66、7 這七本書，「當然」是虛構的，但是，張大春卻「請」出了已故的歷史小說巨擘高陽來「背書」，眉批夾注的評點、闡發不說，更語重心長「點明」其間的「可能奧秘」。