www.howtopronounce.com/bukh The third example (the bottom one) is closest to being correct. The oo sound as in book not quite there as it needs to be drawn out a little longer, imagine if it were boook rather than book.
A chook went into the library and said to the librarian "Book, book. book."
So the librarian gives it three books.
Chook comes back 5 mins later with the books, dumps them and again says "Book, book, book."
The librarian dutifully gives three more books.
Chook comes back 5 mins later and the same thing happens.
Third time the chook comes back and the librarian gives it three more books but she can't believe the chook can read so fast so she follows the chook down the street and around the corner where the chook dumps the books in front of the frog who says "Redditt, redditt, redditt."