«The practice of faith has ever and always been the only available source of faith.» (firstthings.com)
Growing populations throughout the Great Plains region are also demanding more municipal water from the only available source: the aquifer. (scientificamerican.com)
However, the precipitation it does receive is critical, Pettersen says, «because it is the only available source for building up mass on the ice sheet.» (sciencedaily.com)