Yelp is nothing at the moment other than a setup profile. I haven't decided if I want to go PPC or lead purchasing. I don't want to waste funds and know very little about the effectiveness of PPC advertising.If you are buying leads from a lead generator over the internet I would classify those as Primary lead Source: Internet, and a Secondary Lead Source of: Referral Service, and lump them all together. If you want to track each one individually make another column.
I'm not sure what Yelp is, if you're paying for leads it would be a Referral Service, if you're paying for clicks it is Pay Per Click
I lump Repeat & Referral together as a primary lead source, Secondary lead sources are Past Customer, Potential Customer, Friend etc. I also have a field where I record the name of the person that gave me the referral.
Would you go with the generic setup I have or scrap it for a more detailed monthly setup?