Method of collecting documents of the same category by using title number and auxiliary classification number;

The paper has summarized and reviewed the improvement and application of studies on title number,points out the insufficiency in studies on title number.

This paper distinguished a book of the same categories employing alike title number methodology from different edition,also it suggested means of classification about the different edition number of edition and volume number.

The paper introduees category number and author number and analyzes the significance of focusing a topic under the scome category mumber classification number and into practice.

The writer recommend the way to improve the sort number in Bibliographical work,and put the method in use.

In order to further stress the advantages of the class and order number of books,this paper summarizes the same kind of books which uses the same class and order number but is difficult to be identified,and gives different assistant identifications.

The paper raises opinions of using class and order number to collect books of different classes but of the same author in the same kind.

The highly precise magnetochronologic study indicates that the age of Xiaganchaigou and Shangganchaigou Formations in Hongsanhan No.