References
Yu, K. C., and R. Shuping. 2019. The W40 cluster region with the UKIDSS Galactic Plane Survey and Gaia. In preparation.
Yu, K. C., and R. Shuping. 2018. Characterizing the W40 cluster region with the UKIDSS Galactic Plane Survey. American Astronomical Society Meeting #231, Bulletin of the American Astronomical Society 448.04.
Shuping, R. Y., W. D. Vacca, M. Kassis, and K. C. Yu. 2012. Spectral classification of the brightest objects in the galactic star-forming region W40. The Astronomical Journal 144(4):116–127.