"Extrait, sans changement de pagination, de The American midland naturalist, 19: 489-558, 1938."
"Based on a lecture entitled 'The vanishing floras of northeastern North America' and delivered on the occasion of 'The Julius Arthur Nieuwland memorial exercises' held ... at the University of Notre Dame, January 10, 1937"--Foot-note, p. 489.
Includes bibliographical references (pages 557-558).