{"version":"1.0","type":"rich","provider_name":"EbookNetworking","provider_url":"https://www.ebooknetworking.net","title":"Introduction to the calculus of variations","author_name":"William Elwood Byerly","thumbnail_url":"https://www.ebooknetworking.net/books/117/672/big1176720805.jpg","thumbnail_width":330,"thumbnail_height":500,"html":"<a href=\"https://www.ebooknetworking.net/books_detail-1176720805.html\">Introduction to the calculus of variations</a>","width":400,"height":300}