Amonette, F. Alayne Street-Perrott, Johannes Lehmann, Stephen Joseph; Amonette; Street-Perrott; Lehmann; Joseph. Sustainable biochar to mitigate global
Schleicher und Böhmen. Prague, Karolinum (1995). ISBN 80-7066-942-X Winfred P. Lehmann, A Reader in Nineteenth Century Historical Indo-European Linguistics, Chapter