BibTeX, biblatex and biber ⇒ reference with only "author et al."

[mau]

hello,
I need to finish a report by Monday. I am using Bibtex and natbib with the "plain" style, but I need to have references without second authors (so just first author followed by 'et al.'). Does anybody know how I can adapt the plain.bst file to obtain this?

Many thanks!