The book "Từ điển song ngữ Hán Việt Chỉ nam ngọc âm giải nghĩa" ("Chỉ nam ngọc âm giải nghĩa: A Sino-Vietnamese Disyllabic Dictionary with Explanations") by Hoàng Thị Ngọ is a synthesis of her research findings and investigations into the original "Chỉ nam ngọc âm giải nghĩa" over the past decade. Hoàng Thị Ngọ carefully re-examined the Hán-Nôm text in an effort to further refine and build upon the annotated version previously established by Dr. Trần Xuân Ngọc Lan. Her work clarifies a range of issues related to the manuscript, authorship, dating, as well as historical phonology and archaic vocabulary. Most notably, she demonstrates that the lục bát (six-eight syllable) verse form was used to express the dictionary’s entries, constituting the earliest known written evidence of the lục bát form in Vietnamese medieval literature. This is the 2020 reprint, revised and expanded compared to the 2016 edition.