Automatically abbreviate authors first names in bibtex

I had all my references (50+) with all author names spelled out, but was told to abbreviate first names to one letter (Indeed that looks better IMO too). I didn't want to do that manually, and found out that this can automatically be done by using the bibtex style "abbrv". So I set it in my latex document with

\bibliographystyle{abbrv}

Comments

combination with unsrt?

Can that be combined with:

\bibliographystyle{unsrt}

?

Hmm, I am able to use both,

Hmm, I am able to use both, like:
\bibliographystyle{abbrv}
\bibliographystyle{unsrt}
...but I can't really see a difference from using abbrv alone.