It's easy to cite LitCharts for use in academic papers and reports.
MLA
Arn, Jackson. "Mere Christianity." LitCharts. LitCharts LLC, 12 Jan 2017. Web. 22 Oct 2020.
Chicago
Arn, Jackson. "Mere Christianity." LitCharts LLC, January 12, 2017. Retrieved October 22, 2020. https://www.litcharts.com/lit/mere-christianity.