@PhdthesisMisc{A86_881, author = {Alejandro Amrein}, title = {A simplified CF-approximation}, note = {Dis_no 8183, PD Dr. Martin Gutknecht}, school = {ETH Z{\"u}rich}, doi = {http://dx.doi.org/10.3929/ethz-a-000412273}, year = {1986} }