Notes on the Ratnakūṭa Collection by K. Priscilla Pedersen a downloadable PDf
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Boucher, Daniel. Bodhisattvas of the forest and the formation of the Mahāyāna - A Study and Translation of the Rāṣṭrapālaparipṛcchā-sūtra, Institute for the Study of Buddhist Traditions, 2008
Glass, Andrew. Four Gandhari Samyuktagama Sutras: Senior Kharosthi Fragment 5. Univ of Washington Pr, 2008.
Glass, Andrew, and Richard Salomon. A Gandhari Version of the Rhinoceros Sutra: British Library Kharosthi Fragment 5B. Univ of Washington Pr, 2001.
Silk, Jonathan A..The Origins and the History of the Mahāratnakūta Tradition of Mahayana Buddhism With a Study of the Ratna rāśi Sutra and Related Materials, Dissertation, University of Michigan. (1994)
Chang, Garma C. C., ed. A Treasury of Mahayana Sutras: Selections from the Maharatnakuta Sutra. annotated edition. Pennsylvania State University Press, 2008.
Nattier, Jan. Few Good Men: The Bodhisattva Path According to the Inquiry of Ugra (Ugrapariprccha). New edition. Univ of Hawaii Pr, 2005.