Where to find hub cartridge bearings

[Doug]

I've got an older hub that needs new cartridge bearings. I can mic
the things to get exact dimensions. Using those specs, I've been
hitting sites that I've Googled.

Is it simply a matter of reading through bearing specs until I find
the right size, or using the specs can I find some table which tells
the "type" or something? Like, ID=10mm, OD=25mm is a type 2309. Etc.

Any tips would be helpful. http://www.biketoolsetc.com and other such
sites list a slew of bearings that I've been reading through.

Thanks, Doug