History of linguistics (19th century) ; History of linguistics (20th century) ; Evolution (theory of) ; Theory of evolution ; Komplexes System; Complex system; Emergenztheorie; Emergence (theory of) ; Systems theory ; Jugendliche (Sprachverhalten) ; Adolescents (language behavior) ; Jargon; Youth language ; Sprachwandel (morph.) ; Language change (morph.) ; Morphological change ; History of language (sociolinguistics) ; Language change ; Taxonomic linguistics; Structuralism ; German