Антропонімічні аргументи в історії слов’янської фонеми

The Proto-Slavonic language never knew the phoneme , since it had bilabial sonant , which, contrary to the voiced consonants, did not require its voiceless pair. Consequently, when numerous Christian names with sound [f] came to the Slavs with the adoption of Christianity, those Slavonic languages, including Ukrainian, that preserved the sonant , resisted the foreign [f] by various substitutions, while they substituted sonant by voiced , whereas Russian accepted the sound [f] more loyally.