TY - JOUR AU - Vogel, K AU - Diddams, Scott AU - Oates, Christopher AU - Curtis, E AU - Rafac, R AU - Bergquist, James AU - Fox, Richard AU - Lee, W AU - Hollberg, Leo C2 - Optics Letters DA - 2001-01-01 00:01:00 LA - en M1 - 26 PB - Optics Letters PY - 2001 TI - Direct Comparison of Two Cold-Atom-Based Optical Frequency Standards by Using a Femtosecond-Laser Comb ER -