Yamada, Yukihiro. A Buhi Bikol Vocabulary; Bulletin of the Faculty of Education, Kochi University, No. 24, Series I. Kochi: Faculty of Education, Kochi University (1972)

Professor Yukihiro Yamada authored the first known published scholarly article and vocabulary list on the Boie'nen language, "A Buhi Bikol Vocabulary" (1972), featuring 513 lexemes. Thirty years later, Yamada mailed a revised copy to Alfonso T. Claveria, a native Boie'nen speaker, suggesting changes to the language's notation system, including:

- Apostrophe (') for glottal stop instead of ʔ

- "ng" for ŋ

- "e" for ə

These revisions will help ease the “ordinary writing of Boie’nen using the (then ubiquitous) typewriter machine” said Professor Yamada.

Alfonso Claveria later introduced the concept of a half-stop or inter-syllabic pause, denoted by a dash (-), which marks syllable separation or rhythmic cadence without altering pitch or pronunciation.

About Professor Yamada:

Yukihiro Yamada is a graduate of St. Paul's (Rikkyo) University and holds training in linguistics and language education from the International Christian University (ICU), Tokyo. His academic and teaching career spans institutions in the Philippines (University of the Philippines, Lyceum of the Philippines, and Philippine Women's University), the University of Hawaii, Kochi University (Japan), and Himeji Dokkyo University (Japan).