Nature. doi:10.1038/nature.2013.12963. ↑ "Herschel discovers water vapour around dwarf planet Ceres". European Space Agency. Retrieved 10 February 2014. ↑ http://live.huffingtonpost.com/r/highlight/scientists-discover-where-earths-water-originated/564ba93d99ec6d09c3000126?source=gravityRR&cps=gravity_5060_-7528146454370360511 ↑ Drake, Michael J.