KMC ver. 2 algorithm was described in the paper:
S. Deorowicz, M. Kokot, Sz. Grabowski, A. Debudaj-Grabysz, KMC 2: Fast and resource-frugal k-mer counting. Bioinformatics. 2015. doi: 10.1093/bioinformatics/btv022. (Draft: http://arxiv.org/abs/1407.1507).

The KMC 1 software is accompanied by a research paper:
Sebastian Deorowicz, Agnieszka Debudaj-Grabysz, Szymon Grabowski: Disk-based k-mer counting on a PC. BMC Bioinformatics 2013, 14:160