The descriptions of Revised Kneser pruning and Kneser-Ney growing can be found in the paper Vesa Siivola and Teemu Hirsimäki and Sami Virpioja, "On Growing and Pruning Kneser-Ney Smoothed N-Gram Models", IEEE Transactions on Speech, Audio and Language Processing, 15(5):1617-1624, 2007 (available at https://sites.google.com/site/vesassiivola/publications/TASLP2007.pdf).