The plugin add a shortcode in order to link a paper using its doi code. You can also use an other shortcode to resolve doi code and publish a full citation apa formatted. It is also a shortcode for manual citations.
The plugin send the doi code to [Crossref Metadata Search](https://search.crossref.org/), get the information and publish a full citation in apa standard with the shortcode [ctdoiresolve ...].
**Digital Object Identifier**, or *DOI*, is a persistent identifier used to uniquely identify objects, standardized by the **International Organization for Standardization** (*ISO*). DOIs are mainly used to identify academic, professional, and government information, such as journal articles, research reports and data sets, official publications.
***Citations tools*** uses the [CrossRef Metadata API](http://search.crossref.org/help/api) to retrieve complete publication information using the doi code as a search query. CrossRef is a part of the [doi system](https://dx.doi.org/).
1. Extract the citations-tools.zip file and upload its contents to the /wp-content/plugins/ directory. Alternately, you can install directly from the Plugin directory within your WordPress Install.
2. Activate the plugin through the "Plugins" menu in WordPress.