ڳولا نتيجا

1038/ngeo325. Bibcode: 2008NatGe...1..636E. http://www.physics.ohio-state.edu/~wilkins/energy/Resources/Essays/ngeo325.pdf.xpdf. Retrieved 22 October 2010.  Emmett...

Applied Geography 43: 81–86. doi:10.1016/j.apgeog.2013.05.012. Bibcode: 2013AppGe..43...81C. https://www.sciencedirect.com/science/article/abs/pii/S0143622813001367...