[1] M. Takamoto, F. Hong, R. Higashi, and H. Katori, Nature 19, 321 (2005).
[2] E. Zang and J. Cao, Acta Opt. Sin. (in Chinese) 3, 931 (2003).
[3] R. L. Targat, J.-J. Zondy, and P. Lemonde, Opt. Commun. 247, 471 (2005).
[4] A. D. Saenz, "461 nm Laser for Studies in Ultracold Neutral Strontium" Master Thesis (Rice University, 2005).
[5] Y. Asakawa, H. Kumagai, K. Midorikawa, and M. Obara, Opt. Commun. 217, 311 (2003).
[6] H. R. Telle, D. Meschede, and T. W. Hansch, Opt. Lett. 15, 532 (1990).
[8] B. Lu, T. Vogt, X. Liu, X. Zhou, and X. Chen, Chin. Opt. Lett. 9, 091403 (2011).
[9] T. W. Hansch and B. Couillaud, Opt. Commun. 35, 441 (1980).
[10] A. Hemmerich, D. H. McIntyre, C. Zimmermann, and T. W. Hansch, Opt. Lett. 7, 372 (1990).