Citation styles preferred by the National Centre for Research on Europe include Harvard and APA.
Whatever style you use it is important to be consistent.
Harvard Citation Style
There are variations in the Harvard Style. UC supports Harvard Canterbury. Harvard is an in-text citation style.
The Library has extensive APA guidelines.
Citing EU Documents
In both styles citing EU official documents can be challenging. See the examples in:
Leeds Harvard EU Legislation
The University of Canterbury supports the use of EndNote software to assist with the management of bibliographies.
It is available from all campus student install computers and can also be downloaded to your laptop or other personal devices.
Guidelines for separating your bibliography into categories.