I'm trying to determine the industry leading online bookselling
marketplaces in the Cantonese and Mandarin languages (serving the
Chinese market).

For reference: A bookselling marketplace allows INDEPENDENT vendors to
list their inventory for sale directly to online buyers. Ebay is an
example of a US-based general markeplace. Abebooks and Alibris and
examples of US based bookselling marketplaces.

To find this out, it would likely be as simple as doing a google
search (or the appropriate Mandarin/Cantonese equivalent search
engine) on some typical bookselling terms: "bookselling", "used
books", "rare books", "book marketplaces". Some basic browsing should
be able to determine what are real players and what are small
operations. Please note that I am looking for marketplaces for
independent sellers- and not a single retailer like a Barnes and Noble
or a Amazon. I would only need 3 or so examples per languauges (if
indeed there are three examples). Please include the company names and
Links so that I can research further myself.