When writing a thesis, is it acceptable practice to cite only the URL of referenced research papers where they are published electronically? Or is it compulsory to give proper authors, title, year of publication, etc... information?


Data mining is the process of analyzing large data sets in order to discover hidden patterns within these data sets.[1] Stock market prices do not follow random walk.[2]

[1] http://books.google.co.uk/books?id=5FIEAwyn9aoC

[2] http://rfs.oxfordjournals.org/content/1/1/41.short

  • It happened to me twice: I have once cited an article from wikipedia. Try giving the authors and date of publication for that one ;), the second time was to give the url where my source code could be found.
    – Gopi
    Commented May 5, 2012 at 22:05
  • If one acquires information from Wikipedia, one should acknowledge this, otherwise one is being dishonest, quite literally. That this information is "disqualified" somehow seems to argue that one must never look at Wiki, because one is acquiring inadmissible info? What? This is crazy! :) Commented Oct 7, 2012 at 16:34
  • If you use LaTeX: biblatex has the type "online" which you can use to cite online resources... Commented Oct 22, 2015 at 19:23

10 Answers 10


No, it's not OK to cite URLs because firstly, you are citing ONLY the URL! The URL could change at any given time without notice. Also, you are assuming that everyone is reading your paper electronically and has access to the internet.

You NEED to give the name of the paper, the author(s), the Journal it was published in and the year it was published.

  • 6
    You may not be citing a paper. For example, you might be citing software, or a news article.
    – Suresh
    Commented May 6, 2012 at 5:33
  • 7
    ...in which case you still need to cite the author(s), date, and (for news articles) the name of the newspaper/magazine/website.
    – JeffE
    Commented May 6, 2012 at 6:44
  • 6
    However, using DOI (Digital object identifier) link (i.e. http://dx.doi.org/...) gives a permalink to a paper. However, it is a good to add it to the citation, not to replace it with it. Another choice is using arXiv id (e.g. http://arxiv.org/abs/...); in fact it is often used instead of the full citations (but on slides are other informal things, not in papers/theses). Commented May 6, 2012 at 16:17
  • I disagree with @Suresh (but I did that in the past) : software must be put in footnotes, unless you're citing a paper describing a software. Commented Oct 7, 2012 at 16:01
  • I would bet that DOI will outlive physical libraries of journals. Commented Oct 7, 2012 at 20:10

Absolutely not! The other answers mention impermanence of URLs, which is an issue, but not, I think, the most important one. The most important reason is that some of the information in a citation, especially the author and year of publication, is important context for interpreting a citation, and is therefore essential content to the paper itself.

  • 1
    I agree, but should add that the impermanence of the URL is closer to a non-issue in some cases. Take, for example, the arXiv which is rapidly gaining traction in the academic world. If you want to cite an arXiv paper, the most important part is the url (which is permanent).
    – Shep
    Commented May 5, 2012 at 21:41
  • 2
    @Shep: The arXiv identifier is certainly permanent, but in principle the URL might change (and in fact it has changed in the past). One common citation method, which is recommended by the arXiv, is "arXiv:1205.0542", or "arXiv:1205.0542v1" if you want to specify the version number. You can link this to the URL arXiv.org/abs/1205.0542 when someone clicks on it, but in the text it is best to focus on the arXiv identifier instead. Commented May 6, 2012 at 5:45

The point of a bibliography is not only to identify your sources, but to allow your readers to read those sources themselves, at some indefinite time in the future. Bare URLs rarely serve that function, in part because URLs are (by design) transient, and in part because you cannot assume that your unknown future reader will have internet access. This is the same reason why citations should still include page numbers, even though a quick Google search on the title and authors almost always finds the paper.

On the other hand, books go out of print, library subscriptions lapse, some conference proceedings are only distributed online, some papers are still preprints, and sometimes the source in question is a blog, a usenet post, a source code repository, or a StackExchange question. For sources without permanent reliable offline access, I think you must include a URL in your bibliography, despite its transience, in addition to as much traditional identifying information (authors, title, journal/conference/book title, page numbers, date) as possible.


The MLA Style guide (via Indiana University) says the following:

World Wide Web Sites:

There are many different kinds of web sites, so it is impossible to give just one set of precise instructions for citation format. If you can not find some of the information needed, cite what is available. The following Works Cited/Bibliography examples are only guidelines; utilize the MLA Handbook for Writers of Research Papers for additional examples.

What you need (at minimum):

   Site title (if there is no title use a description such as "Home Page")
    Date you accessed the information

What you need (if available):

   Author(s)/Editor(s) name
    Publication or last update date
    Organization/Institution name associated with the site

Because URL are (usually) not eternal, but hopefully your publication is, then I wouldn't advise to only put an URL, especially for books or paper. It doesn't add much to make a full biblio item, that can of course include the URL! Note that Bibtex has a special field for url, but you can also add it as a note.


URL sources are a grey area. When possible, cite the original source. For example if you are citing books.google.* , then you need to cite that book as a book and not a URL. For academic publications, there is an OPTIONAL URL field you may use, but this should be in addition to citing the original conference/journal/workshop/etc.

There are circumstances where a URL is the best identifier of the resource, and in those cases, you'll have to cite the URL. For example, I used a URL resource from the libary of congress because it was unpublished historical (circa 1890AD) blueprints scanned into their library.


The best practice is to include standard bibliographic information, a relatively stable hypertext link for current readers (e.g. to the ArXiv), and the DOI.


(I think:) Definitely give a URL if there is one, with the date you down/up-loaded the paper, and perhaps give a revision date of the paper, if it itself gives one.

AND give the more traditional reference information as well.

The URL allows people to find an e-copy, at least for a while. The conventional references do not necessarily produce copies accessible through the internet, though sometimes they do.

For the time being, these two sorts of citations give different information, have different utilities. One may take the pose that one makes the other irrelevant, but I think this is not accurate. The common "objections" to internet-accessible things, that they are "transient", while physical references are "permanent", is disingenuous, upon some thought. First, many good things are transient, which is not an argument against them! Second, physical references are equally transient, if in a different way... usually that many different libraries throughout the world maintain "cached" copies. Well, maybe Google has cached the now-gone document at a vanished URL? :)

In summary, operationally, give all the information you have in citations, even while recognizing that some of it has an expiration date.


For everything that have been reviewed AND permanently archived then the bibliography is fine. For all the rest footnotes are the place to be.


No, it is clearly and everyone agrees, not acceptable practice to cite only the URL. So download a PDF copy of the exact web page. You can even state in the publication that you have a copy of the exact PDF which corresponds with your reference. If anyone asks you for sa copy of the PDF, you may wish to do one of the following:

  1. Immediately give them the pdf (which may be a license violation). I feel comfortable to do this, in some situations, but not all.


  1. Tell them you would like to give them your saved copy, after they convince you, that the web site will allow you to give them a copy.

It is not your problem, if the web site will not give you permission, to give others a copy of the saved PDF. However a license violation would be your fault.

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