I misremembered, sorry: it's only available in Zanark. To gain access to the higher floor you must bring a rare book. One of the easiest ones to find is in a store at Solina's docks (save first, in case you don't want to get mind-controlled there). You must search one of the bookcases there multiple times, until you stop finding new books, and then you can ask the shop owner to buy the last book.
Bring that book to Zanark, and then you can go to the highest floor, where you can search for the chessbook (in the advanced topics).