{"version":"1.0","type":"rich","provider_name":"EbookNetworking","provider_url":"https://www.ebooknetworking.net","title":"Ray Optics, Fermat's Principle, and Applications to General Relativity","author_name":"Volker Perlick","thumbnail_url":"https://www.ebooknetworking.net/books/354/066/big3540668985.jpg","thumbnail_width":330,"thumbnail_height":500,"html":"<a href=\"https://www.ebooknetworking.net/books_detail-3540668985.html\">Ray Optics, Fermat&#039;s Principle, and Applications to General Relativity</a>","width":400,"height":300}