SQL Alternatives? Please =)

Heya,

I was working on an sql problem and solved it:

SELECT planten.PLANTNAAM, planten.SOORT
FROM PLANTEN AS planten
WHERE (((planten.ART_CODE) Not In
(SELECT offertes.ART_CO FROM OFFERTES offertes, BESTELRG bestelrg, BESTEL bestel
WHERE offertes.ART_CO_LEV = bestelrg.ART_CO_LEV
AND bestel.Bestelnr=bestelrg.bestelnr
AND bestel.Lev_code=offertes.lev_code)));

However, I need find an alternative to NOT IN if one exists and isn't too long? if anybody can offer an alternative it would be appreciated :)