Keitel, Christoph H. Division Prof. Dr. Christoph H. Keitel, MPI for Nuclear Physics, Max Planck Society;
http://link.aps.org/doi/10.1103/PhysRevA.46.1468 (Verlagsversion)
Fleischhauer, M., Keitel, C. H., Scully, M. O., Su, C., Ulrich, B. T., & Zhu, S. Y. (1992). Resonantly enhanced refractive index without absorption via atomic coherence. Physical Review. A, 46(3), 1468-1487. doi:10.1103/PhysRevA.46.1468.