riichi_mahjong_snadno_a_rychle.pdf (CZ) (pdf)
A simplified explanation of rules for beginners.
riichirules_CZ.pdf (CZ) (pdf)
Unofficial Czech translation of the rules of the European Mahjong Association by Petr Bajgar.
mahjong-europe.org/ (EN/FR/PL/SP) (pdf)
Rules according the European Mahjong Association.