Published in 2022 in Volume 60 of Tōnan Ajia Kenkyū (東南アジア研究, Southeast Asian Studies), this Japanese-language article by Shimizu Masaaki (清水政明), titled “Dialectal Features of Nôm Characters of Phật Thuyết Thiên Địa Bát Dương Kinh,” examines the dialectal features reflected in the Nôm characters used in the Sino-Nôm version of Phật Thuyết Thiên Địa Bát Dương Kinh, a text preserved at Canh Phuoc Temple in Bangkok, Thailand. Approaching the text from the perspectives of historical phonology and lexicography, the study analyzes the phonetic components of individual Nôm characters to identify dialectal features embedded in their formation and usage. The analysis reveals a number of characteristics associated with Central and Southern Vietnamese dialects, demonstrating that Nôm characters can preserve important evidence of regional linguistic variation and the historical development of the Vietnamese language. The article also situates Phật Thuyết Thiên Địa Bát Dương Kinh within a broader textual and historical context. Through an examination of its contents, dating, publication history, and writing system, the author suggests that the text may have been produced in or after the nineteenth century and considers how its linguistic characteristics relate to the geographical distribution of Vietnamese dialects. Tables and maps included in the study illustrate phonological correspondences among Northern, Central, and Southern Vietnamese and the geographical distribution of several linguistic phenomena reflected in the Nôm characters. More broadly, the study demonstrates how analysis of the structure and phonetic components of Nôm characters can provide important evidence for reconstructing the phonological history and dialectal development of Vietnamese. The author suggests that some features found in the text may reflect changes in Southern Vietnamese dialects from approximately the nineteenth to the early twentieth century, highlighting the value of Sino-Nôm materials for research on Vietnamese historical linguistics, dialectology, historical phonology, and the history of Vietnamese writing systems.