Url,Type,Title,Publisher Place,Publisher,Date,Authors,Volume,Language,Pages https://www.biodiversitylibrary.org/page/3525772,Book,"Index filicum,sive, Enumeratio omnium generum specierumque filicum et Hydropteridum ab anno 1753 ad finem anni 1905 descriptorium : adjectis synonymis principalibus, area geographica, etc ",Hafniae [Copenhagen],H. Hagerup,1934,"Christensen, Carl, 1872 -1942",Suppl. 3 1917-33,,Page 22