In any piece of written work in which you have cited references to published works, it is necessary to provide a bibliography, or list of references, at the end of your work.
You should provide only one such list. For some reason, many people have acquired the curious belief that they should give two lists: one list of all the references in the order they occur, and a second alphabetical list, or something similar. This silly practice is a pointless waste of time and paper: there should be only one list of references, and the references in your text should direct the reader straight to that list, as explained earlier.
The precise form of your bibliography may vary slightly, depending on what system you have used for citing references in your document. Here I shall assume that you have used the Harvard system, as recommended.
The bibliography is put into alphabetical order according to the surnames of the authors and editors you are citing. If you cite two authors with the same surname, put them in alphabetical order by their first names or initials. If you cite several different works by the same author, put them in date order, earliest to latest. If you have two or more works with the same author and the same date, use the a, b, c system already described. When you cite multiple works by the same author, that author's name need be written out only once; for succeeding works, you can use a horizontal line instead of repeating the name. A book with no author or editor is listed alphabetically by its title.
There are just three types of work which are very commonly cited in bibliographies: books, articles in books, and articles in journals. For each type, the form of the reference is slightly different, but, above all, the reference must be complete.
For a book, you must give the name(s) of the author(s) or editor(s), the date, the title, the place of publication and the name of the publisher. For an article in a book, you must give the name(s) of the author(s), the title of the article and the first and last pages, as well as full information on the book itself, as just described. For an article in a journal, you must give the name(s) of the author(s), the date, the title of the article, the name of the journal, the volume number and the first and last pages. Names of authors should be given just as they appear in their publications.
If you are citing two or more articles from a single book, you can put that book into your list as usual, and cross-refer each article to that book, as shown below.
There are several slightly different systems for arranging and punctuating references in a bibliography, almost all of them acceptable. They differ chiefly in whether they use full stops or commas to separate parts of the reference, in whether they put quotation marks around the titles of articles, and in where they place the date. I recommend full stops rather than commas, single quotation marks around titles of articles, and the placing of the date immediately after the author's name, and that is the system used in my examples below. Standard sources like The MLA Style Guide often recommend slightly different systems, and your tutor or publisher may insist upon one of these; in that case, you should fall into line, but make sure your references are complete.
Here is a sample bibliography:
One further point. If you have to enter a title in your alphabetical list, ignore the words the, a and an at the beginning. So, a book entitled A History of Footwear would be listed under H, not under A, and the newspaper called The Guardian would be listed as Guardian, under G.
If you are using the number system for citing references, then, of course, each item in your bibliography must be preceded by its number. You should still, however, put those items in alphabetical order. Many people who use the number system simply list the items in the order in which they occur in the text. This allows the reader to find a particular reference, all right, but she can no longer glance at your bibliography to see if particular authors or works are present. All readers will find this unhelpful, at best, and a university tutor is likely to be very annoyed.