The strength of a research work be it PhD essay writing or journal writing is measured in its bibliography. It differs in its intensity, impact and effects from reference. A reference could give a brief understanding of various books, materials or journals which are referred by the research scholar. It may not be adequate and it could not be able to serve the purpose to a larger extent.
Bibliography is the proper professional way and approach to describe how a research work or article or already completed PhD work has been referred. There are various styles to give it. Harvard style, MLA referencing are different styles of presenting the details of author, year, title, research journal name, journal number, page number. Scholars also give the google citation by clicking that link you could reach the article and it can be verified. They also mention ISSN no and year to make it fool proof.
It is a method of stating in the research work how professionally the referencing part has been carried out, intensively and exhaustively by following global standards of referencing. The font size, side index margin, spacing width everything is predefined and explicitly stated by Universities around the world.