Sterr U, Legero T, Kessler T, Schnatz H, Grosche G, Terra O, Riehle F.  2009.  Ultrastable lasers: new developments and applications. Time and Frequency Metrology IIProceedings of SPIE. :74310A-74310A-14. Abstract
Schnatz H, Terra O, Predehl K, Feldmann T, Legero T, Lipphardt B, Sterr U, Grosche G, Hänsch TW, Holzwarth R et al..  2009.  Phase-coherent frequency comparison of optical clocks using a telecommunication fiber link. Frequency Control Symposium, 2009 Joint with the 22nd European Frequency and Time forum. IEEE International. :807-812. Abstract
Schnatz H, Terra O, Predehl K, Feldmann T, Legero T, Lipphardt B, Sterr U, Grosche G, Holzwarth R, Hänsch TW et al..  2010.  Phase-coherent frequency comparison of optical clocks using a telecommunication fiber link. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. 57(1):175-181. Abstract