Mathew, Santhosh. "Introductory Astronomy for Undergraduates". OER Commons. Institute for the Study of Knowledge Management in Education, 23 Aug. 2017. Web. 29 Apr. 2024. <https://oercommons.org/authoring/23762-introductory-astronomy-for-undergraduates>.
Mathew, S. (2017, August 23). Introductory Astronomy for Undergraduates. OER Commons. Retrieved April 29, 2024, from https://oercommons.org/authoring/23762-introductory-astronomy-for-undergraduates.