It's easy to cite LitCharts for use in academic papers and reports.
Parfitt, Georgina. "Sir Gawain and the Green Knight." <em>LitCharts.</em> LitCharts LLC, 3 Sep 2013. Web. 20 Aug 2017.
Parfitt, Georgina. "<em>Sir Gawain and the Green Knight</em>." LitCharts LLC, September 3, 2013. Retrieved August 20, 2017. http://www.litcharts.com/lit/sir-gawain-and-the-green-knight.