When citing an electronic source, it is better to risk providing too much information rather than too little. Be sure that your reader has enough information to go back to your source if necessary. Although a citation to a publication in electronic format follows basically the same principles as a citation to a paper document, citing an electronic publication or content from a website may present a few peculiar challenges. For instance:
Most citation styles prefer that you include the DOI (when available) for online sources such as articles. The term DOI is an acronym for Digital Object Identifier and unlike URLs, DOIs are uniquely assigned and will stay with the source even when the site structure or platform of access changes.
The DOI is a numeric or alphanumeric string of text that may be used as an URL (or search term) to locate an online resource. The DOI may look something like this: doi:10.00/00.00/00000/0000, or this http://doi.org/10.0000/abcd.00/0000
To locate the DOI, look on the first page of the article. Other common places to locate the DOI may be the footer, the record page, or the publisher's website. If you are having trouble locating a DOI, try checking https://www.crossref.org/ or https://www.datacite.org/.
For online sources without DOIs, it is extremely important to make sure the URL used to point back to the source is not a search string or a proxy link. It is usually best to go to the publisher's home site if you are unsure whether the link you used to access the source is the permanent link for the source.