History of linguistics (20th century) ; History of linguistics (21st century) ; Chaos theory ; Ökologie und Sprache; Ecology and language; Umweltschutz; Pollution; Umweltbelastung; Ökolinguistik; Ecolinguistics; Klimawandel; Climate change; Language and ecology ; Multilingualism; Polylingualism; Plurilingualism ; Dreisprachige Erziehung; Trilingual education; Multilingual education