I'm sorry but I think that this example is incorrect. Since 'Max' is the subject of the clause (with 'given' being the verb and the 'book' the object), it would then translate to Who was given the book? If the original sentence had been, Casi gave Max the book then it would translate to To whom did Casi give the book? Since Casi would become the subject of the clause. A good trick for remembering whether to use who or whom, incidentally, is to replace the word who or whom with he or him and see which one sounds right. Whom, of course, corresponds to him. So, for example: Who arrived first or whom arrived first? Obviously, using this method, he arrived first sounds much better than him arrived first so the correct word to use would be who. On the other hand, Whom do I love or who do I love? I love him sounds better than I love he so the correct word to use would be whom.