concentrated rays of the sun as it crossed the line. HearstMagazines. Popular Mechanics. HearstMagazines. 1911-07: 1. ISSN 0032-4558. As the sun works around
[2019-05-14]. (原始内容存档于2008-04-06). HearstMagazines. Popular Mechanics. Popular Mechanics Magazine (HearstMagazines). February 1983: 107. ISSN 0032-4558