My books do not sell, but ironically I found that they help selling other stuffs. Currently, those books are like "passport" to in collecting community and are well known in the world. Viewers, especially new collectors, gain some confidence by seeing those books listed for sale by the same seller. The logic might be "You have not read those books yet? you're most likely clueless.", or, opposite.
That's a new use of those books. An unexpected side effect
