求助:generalists and specialists in retailing

Dear all,

Can someone give me suggestions regarding identifying a subset of retailing institutions? These institutions should meet the following two criteria. 1) Both generalists and specialists coexist in the same market. 2) These generalists and specialists are in a market with scale economies and crowding, or at least largely/partially with scales of economies. The example about newspapers might help you understand the criteria better. We can treat national newspaper publishers as generalists, and treat local newspaper publishers as specialists. But now I need examples in retailing institutions with accessible longitudinal data if possible.

Please let me know if you have any suggestions. My email is daviddavid468(A) hotmail.com

Also, if possible, please direct me where to find the longitudinal data for such generalists and specialists. I would really appreciate your help.

Best,

David