Dissertation is a research report or scientific paper written by the author to obtain a certain degree, which is generally divided into three levels: bachelor's thesis, master's thesis and doctoral thesis. In particular, doctoral dissertations are of the highest quality, which are original scientific research works and the focus of collection and utilization.

Dissertation represents different levels of knowledge and is one of the important sources of literature information. Not published in publications, can only be obtained through degree-granting units, designated collection units and private channels.