Hanspach, J., O. Schweiger, I. Kühn, M. Plattner, P. B. Pearman, N. E. Zimmermann, and J. Settele. (2014) Host plant availability potentially limits butterfly distributions under cold environmental conditionsEcography 37 (3): 301-308. http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0587.2013.00195.x/abstract