Eventually Fenchel wrote a book Elementary geometry in hyperbolic space which was intended to put give an approach with would make presentation of Fenchel-Nielsen theory much clearer.
Kalaunan Fenchel wrote isang libro Elementary geometry sa hayperboliko space na kung saan ay inilaan upang ilagay magbigay ng diskarte sa nais na gumawa ng pagtatanghal ng Fenchel-Nielsen teorya marami mas malinaw.