In order to write a good, academic thesis or scientific text, it is important to use sources in the right way. To reference means to give accurate information about the sources you have used, both in your running text and in a list of works cited or a bibliography. This is important as it shows that you have understood the norms of scientific integrity.
Reference tools - keep track of your references
In Endnote you can search in scientific databases, save references and insert them directly into the document you are writing in Word and other Office-programs.
With Zotero, you can collect articles and cite them from Word, OpenOffice and LibreOffice. If you write in LaTeX or RMarkdown, it can be configured to export BibLaTeX automatically.
BibLaTeX is the recommended reference package if you use LaTeX or RMarkdown. It can be used with or without Zotero or other reference management programs.