{"version":"1.0","type":"rich","provider_name":"EbookNetworking","provider_url":"https://www.ebooknetworking.net","title":"Methods & results: Secular variation of the magnetic declination in the United States & at some foreign stations","author_name":"U.S. Coast and Geodetic Survey.","thumbnail_url":"https://www.ebooknetworking.net/books/B00/3SW/bigB003SWZR96.jpg","thumbnail_width":330,"thumbnail_height":500,"html":"<a href=\"https://www.ebooknetworking.net/books_detail-B003SWZR96.html\">Methods &amp; results: Secular variation of the magnetic declination in the United States &amp; at some foreign stations</a>","width":400,"height":300}