1. J. Barnett: The fractional chromatic number and the Hall ratio, PhD thesis, Auburn University, 2016.
2. A. Blumenthal, B. Lidický, R. R. Martin, S. Norin, F. Pfender and J. Volec: Counterexamples to a conjecture of Harris on Hall ratio, arXiv:1811.11116 (2018).
3. M. Cropper, A. Gyárfás and J. Lehel: Hall ratio of the Mycielski graphs, Discrete mathematics 306 (2006), 1988–1990.
4. A. Daneshgar, A. Hilton and P. Johnson: Relations among the fractional chromatic, choice, Hall, and Hall-condition numbers of simple graphs, Discrete Mathematics 241 (2001), 189–199.
5. Z. Dvořák: Asymptotical structure of combinatorial objects, PhD thesis, Charles University in Prague, 2007.