Charles, Mathew. Problems in the Reconstruction of Proto-Philippine Phonology and the Subgrouping of the Philippine Languages. Oceanic Linguistics. 1974, 13 (1/2). JSTOR 3622751. doi:10.2307/3622751.
Blust, Robert. The Greater Central Philippines hypothesis. Oceanic Linguistics. 1991, 30 (2). JSTOR 3623084. doi:10.2307/3623084.
Charles, Mathew. Problems in the Reconstruction of Proto-Philippine Phonology and the Subgrouping of the Philippine Languages. Oceanic Linguistics. 1974, 13 (1/2). JSTOR 3622751. doi:10.2307/3622751.
Blust, Robert. The Greater Central Philippines hypothesis. Oceanic Linguistics. 1991, 30 (2). JSTOR 3623084. doi:10.2307/3623084.