Where can I find the book of Mudora?

Solution 1:

The Book of Mudora is in the library just south of Kakariko village. It's on top of a book shelf that you have to use your Peagus Boots to slam into. After ramming into the book shelf, the book falls off and you can grab it. Here's a video showing this: http://www.youtube.com/watch?v=_SD9FDoyLSk

Here's an image showing it. It's number 15:

Solution 2:

The House of Books is a library located on the southern side of Kakariko Village.

The library itself is elevated on a hill, with a book and quill plaque on the front of the building:

The book of Mudora is located inside on top of a bookshelf to the left, you will need to run at the bookshelf in order to knock the book off the top: