<http://schema.org/mainEntityOfPage>
<http://www.upi.com/Science_News/2012/10/16/Flip-flop-of-Earths-magnetic-field-probed/20911350433864/>
<http://www.upi.com/Science_News/2012/10/16/Flip-flop-of-Earths-magnetic-field-probed/UPI-20911350433864/>