If you want it to abbreviate, then don't use citealp*. That's the command to write the full list.
I think what you're looking for is \citep{key1,key2}. That will put parentheses around it (implicitly) and put the separator in automatically. Like so:
Code: Select all
text~\citep{abba:1958,pappa:2005}.
You will probably want to use
so you get semicolons between citations instead of commas. I think semicolons are the default, but just in case.
I have found the following site useful when working with natbib:
http://merkel.zoneo.net/Latex/natbib.php
It describes a pretty old version, but most of the commands are still the same.