"स्तरिकी": अवतरणों में अंतर

* [https://web.archive.org/web/20091227011139/http://strata.geol.sc.edu/ University of South Carolina Sequence Stratigraphy Web]

* [https://web.archive.org/web/20100612184249/http://snobear.colorado.edu/Markw//Mountains/03/week9.html Front Range stratigraphy]

* [https://web.archive.org/web/20050920105136/http://www.stratigraphy.org/ International Commission on Stratigraphy]

* [https://web.archive.org/web/20090710072148/http://www.uga.edu/~strata/ University of Georgia (USA) Stratigraphy Lab]

* [https://web.archive.org/web/20190327020029/http://www.stratigraphy.net/ Stratigraphy.net] A stratigraphic data provider.