John, Neither is correct because you have not used the relative pronoun "which" properly. If you want to use a relative pronoun here you can use "whose". 1. I bought a book whose name is xxx. 2. I bought a book, whose name is xxx. Other possibilities are -- I bought a book of which the name is xxx."-- I bought a book which is named xxx.-- ------- Am I correct? 1. I bought a book whose name is xxx. = I bought a book named xxx. This refers to only one book. The relative pronoun "whose" introduces a clause that defines the book. No comma is used. 1. I bought a book, whose name is xxx. = I bought a book and its name by the way is xxx. In this sentence "whose" is a non-defining relative pronoun introducing a clause that gives "extra" information about the book. The comma indicates that it is extra information.

I bought a book called ................. I bought a book titled....................

They're both wrong. I bought a book called "...".

neither are correct and both describe buying only a copy of book. to sound casual you may go like this: "I bought a book called xxx." "I bought a lot of books. (title) xxx, xxx, and xxx." > here you may apply a full stop at the end of "books" then enumerate their titles. :)

Nope, they both actually mean the same thing. One just has correct punctuation and one does not. Your sentence would be better phrased: I bought a book, which is named xxx. If you wanted to say I bought books, one which is named xxx, you would say "I bought a lot of books, including xxx."