[Report] Solution/tips for using Natbib with Jabref

[Y.-S. Lu]

Hi guys,
Here is my solution while getting stuck with referencing in the style of "Authoryear". Hope this will help newbies like me. My solution works for me while using the Gummi and Jabref from the official Ubuntu/Mate 18.04 repository.
Remakes here:

1. The format of .bib from Jabref is not supported: The .bib format saved by Jabref is not compatible with Gummi. Since the Jabref using round bracket for the items instead of double quotes.
2. Replacing the round bracket by double quotes. You may check python script.
3. Tips for newbie: Please remember to compile the .bib file for Gummi, and then the Gummi can read the bibliography item for natbib citation.