The spelling of "Pernik region" is determined by its pronunciation, which is /ˈpɛr.nɪk ˈriːdʒən/. The word "Pernik" is pronounced with an initial stress on the first syllable and a short "e" sound as in "pet." The second syllable has an unstressed "i" sound as in "bit." The word "region" is pronounced with stress on the second syllable and a long "e" sound as in "beet." The spelling accurately reflects the phonetic transcription. The Pernik region is located in western Bulgaria and is known for its mining industry.