Sociolinguistics ; Register (sociolinguistics) ; Sociodialectology ; Phonology (sociolinguistics) ; Sociophonology ; History of language ; Periods (historical linguistics) ; English as international medium ; Comparative linguistics; Komparatistik; Indogermanistik; Indoeuropäische Sprachwissenschaft; Indoeuropean linguistics; Proto-Indo-European; Historical comparative linguistics ; English