Despite this card's OCG name being "Books of Dark World", only one book is shown in the artwork.
The Dark World Grimoire may very well be based off of the Necronomicon, a fictitious tome that can summon greater forces, henceforth having a connection with the card's effect.
This card essentially gives any monster the basic effect of "Dark World" monsters, namely the ability to be Special Summon when discarded from the hand (albeit, only when discarded for the hand size limit).
The book appears to be set in right-to-left fashion, the same as how the Japanese read, which is the country Yu-Gi-Oh! originates from.