Papers is a handy tool for organising and sharing references and for citing. It's not free (about 60 dollars per year, if I remember correctly) but worth the money. When adding the Read cube browser extension, you can directly save articles from the browser in your library as PDFs.

The current version (4) is browser-only but they should have the desk-top app ready soon (now there's only the preview version).

Citing in Word is also very easy.