[1] Potter's New Cyclopaedia of Botanical Drugs and Preparations  R.C. Wren Revised by Elizabeth M. Williamson and Fred J Evans. First published in Great Britain in 1988 and reprinted in 1989 and 1994 by the C. W. Daniel Company Limited. 1 Church Path, Saffron Walden Essex. Published 1988 Printed and bound by Biddles, Guildford ISBN 085207 1973.
Images
1. SB Johnny CC BY-SA 3.0
2. pfaf.org USDA-NRCS PLANTS Database / USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.

[1] Drogenkunde, 8th Ed. Heinz, A., Hoppe. Pub. W. de Gruyter (1975) Berlin.
[2] Potter's New Cyclopaedia of Botanical Drugs and Preparations  R.C. Wren Revised by Elizabeth M. Williamson and Fred J Evans. First published in Great Britain in 1988 and reprinted in 1989 and 1994 by the C. W. Daniel Company Limited. 1 Church Path, Saffron Walden Essex. Published 1988 Printed and bound by Biddles, Guildford ISBN 085207 1973.