Ultra-cool dwarfs: new discoveries, proper motions, and improved spectral typing from SDSS and 2MASS photometric colorsZ. H. Zhang, R. S. Pokorny, H. R. A. Jones, D. J. Pinfield, P. S. Chen, Z. Han, D. Chen, M. C. Gálvez-Ortiz and B. BurninghamA&A, 497 2 (2009) 619-633DOI: https://doi.org/10.1051/0004-6361/200810314
