<http://library.cmu.ac.th/cmulebooks/book.php?pid=2689>
<http://schema.org/image>
<http://books.google.co.th/books/content?id=40EsVNsU0bMC&printsec=frontcover&img=1&zoom=1&edge=curl&source=gbs_api>
<http://library.cmu.ac.th/cmulebooks/book.php?pid=6607>