Universal 1950:

Original: Partial or complete denasalization of nasal consonants would occur only in languages with oral-nasal vowel contrast.
Standardized: IF there is partial or complete denasalization of nasal consonants, THEN there is a contrast of oral and nasal vowels.
Keywords: vowel, nasal, oral, denasalization
Domain: phonology
Type: implication
Status: achronic
Quality: statistical (according to author absolute)
Basis: ?
Source: Hyman 1975

Counterexamples: Languages in which there are no phonemic nasal vowels but denasalization of nasal consonants occurs include Asmat, Cantonese, Cham, Diegueno, Korean, and Telefol. However, such denasalization occurs either preconsonantally (as epenthetic stops in English), before high vowels, or after long vowels. Intervocalic denasalization not specifically conditioned by quality or length of the adjacent vowel, then, seems to be limited to languages with distinctive nasal vowels, as Hyman predicted. (Kawasaki 1986: 85)

FP