Using the [crossref.org](https://www.crossref.org/) api, 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 [cpdoiresolve ...].
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.