Verdoorn, Frans. <br/><br/>
Manual of pteridology /  
edited by Fr. Verdoorn ; in collaboration A. H. G. Alston, I. Andersson-Kottö ; foreward by F. O. Bower. 
 - The Hague :   Martinus Nijhoff,   1938. 
 - XX, 640 p. :   il. ;   25 cm.