bibtex natbib square brackets and Lyx

[Alexander Gahr]

Hi I'm currently searching for a bibtechstyle file for my german  
diploma thesis.
There's one style file  for my institute but it seems it don't works  
well with natbib.
So it doesn't show up url and web pages

Also i want to use square brackets in cite

"geschrieben in (Gahr et. al.[2004])"

Is this possible.
THANX Alex