William Stoddart lists the four key authors in the development of the Perennialist school of thought

Author, editor, and translator William Stoddart discusses four authors who were instrumental in the development of the Perennialist school of philosophy in the 20th century: Frithjof Schuon, René Guénon, Ananda Coomaraswamy, and Titus Burckhardt.
William Stoddart (1925-2023) was a prolific Perennialist author, editor, and translator who was active in advancing the understanding of the writings of Frithjof Schuon, Titus Burckhardt, and others, for over 50 years. He translated several of the books of Schuon and Burckhardt, both of whom he was closely with for decades, into English, including many of Schuon’s poems. In addition, for many years Dr. Stoddart served as assistant editor of the influential British journal “Studies in Comparative Religion.”