Nan jing ben yi (Gist of the Classic of Questioning) was written by Hua Shou of the Yuan dynasty. The extant first volume of the original block - printed edition, revised by Lü Fu, was collected in the Library of China Academy of Military Medical Science. There is a preface written by Jie Hong, a Director Ministry of Techndogy in 1366 at the front of this volume. The red seal in the first page showed that it had been collected by Yun Xiang, Pan Zuyin et al. It is highly possible that this volume is the only existing copy.