Firstly, I continue to base most species treatments on personally collected material, rather than on herbarium plants. […] Secondly, I continue to base my concepts on intensive study of a limited suite of collections, rather than superficial study of every packet that comes to hand.
1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, New York, N.Y.: Columbia University Press, page vii