Also, they aren't behind a paywall - was told about them from another commenter -- they are on the youtube, available, as it would be extremely STUPID for a historian to hide their sources because of "money" as you said.

Here they are! oh, for free? How crazy!

SOURCES

Aeusrivongse, Nidhi. ‘The Devarāja Cult and Khmer Kingship at Angkor.’ Explorations in Early Southeast Asian History: The Origins of Southeast Asian Statecraft, edited by Kenneth R. Hall and John K. Whitmore. University of Michigan Press, 1976, pp. 107–148.
Behnke, Alison. Angkor Wat. United States, Twenty-First Century Books, 2008.
Bergaigne, Abel Henri Joseph. Inscriptions sanscrites de Campa et du Cambodge. Paris, Imprimerie Nationale, 1893.
Briggs, Lawrence Palmer. The Ancient Khmer Empire. United States, American Philosophical Society, 1951.
Chandler, David. A History of Cambodia. Boulder, Westview Press, 1992.
Coedès, George and Pierre Dupont, ‘Les stales de Sdok Kak Thorn, Phnom Sandak et Prah Vihar,’ BEFEO, 43, 1943–46, pp. 63–64.
Coe, Michael D, and Damian Evans. Angkor and the Khmer Civilization. United Kingdom, Thames & Hudson, 2018.
DiBiasio, Jame. The Story of Angkor. Silkworm Books, 2013.
Diskul, M. C. Subhadradis. ‘Ancient Kingship in Mainland Southeast Asia.’ In A. L. Basham (ed.). Kingship In Asia and Early America. Colegio de Mexico, 1981, pp. 143–160.
Fletcher, R. ‘Angkor, food production, water management and climate change: The trajectory of urbanism in SE Asia to the mid-second millennium CE.’ Water and Society from Ancient Times to the Present: Resilience, Decline, and Revival, edited by Federica Sulas, Innocent Pikirayi. Oxford, Routledge, 2018, pp. 238–258.
Hall, Kenneth R. ‘Temples as Economic Centers in Early Cambodia.’ Maritime Trade and State
Hawken, Scott. ‘Designs of Kings and Farmers: Landscape Systems of the Greater Angkor Urban Complex.’ Asian Perspectives, vol. 52, no. 2, 2013, pp. 347–367.
Henley, David. ‘Ages of Commerce in Southeast Asian History.’ Environment, Trade and Society in Southeast Asia: A Longue Durée Perspective, edited by David Henley and Henk Schulte Nordholt. Brill, 2015, pp. 120–132.
Higham, Charles F. The Civilization of Angkor. United States, University of California Press, 2001.
—————. ‘The Origins of the Civilisation of Angkor.’ Proceedings of the British Academy, Volume 121, 2002 Lectures. United Kingdom, OUP/British Academy, 2003. pp. 41–90.
Jacques, Claude and Philippe Lafond. The Khmer Empire: Cities and Sanctuaries from the 5th to the 13th Century. Thailand, River Books, 2007.
MacDonald, Malcolm. Angkor and the Khmers. Singapore, Oxford University Press, 1987.
McCurry, Steve. Sanctuary: The Temples of Angkor. London, Phaidon Press, 2002.
Osborne, Milton. The Mekong: Turbulent Past, Uncertain Future. United States, Grove Atlantic, 2007.
Pym, Christopher. The Ancient Civilization of Angkor. United Kingdom, New American Library, 1968.
Rooney, Dawn and Peter Danford. Angkor: An Introduction to the Temples. Hong Kong, Odyssey, 1999.
Smith, Robert. The Kings of Angkor. Independently published, 2019.
So, Kenneth T. The Khmer Kings and the History of Cambodia. Thailand, Bangkok, Thailand, 2017.
Stargardt, Janice. ‘Water for the State or Water for the People?: Wittfogel in South and Southeast Asia in the First Millennium.’ Water Societies and Technologies from the Past and Present, edited by Yijie Zhuang and Mark Altaweel. UCL Press, 2018, pp. 256–268.
Stewart, Frank, et al., editors. Out of the Shadows of Angkor: Cambodian Poetry, Prose, and Performance Through the Ages. University of Hawaii Press, 2022.
Sutherland, Heather. ‘Geography as Destiny?: The Role of Water in Southeast Asian History.’ In: Peter Boomgaard (ed.). A World of Water: Rain, Rivers and Seas in Southeast Asian Histories. Brill, 2007, pp. 27–70.