Any search engine should do the trick. Also, if you've got the particular model of printer you need it for, someone around here may know what it needs. You can find HP or similar cartridges for most of the LaserWriters these days, although if you've got a 4/600 PS, don't go to Office Max--they'll rip you off. (The cartridge retails for $100+; I got one on eBay for $35 instead).