PENTZLIN, Karl. Proposal to add Variation Sequences for Latin and Cyrillic letters [online]. International Organization for Standardization / Organisation Internationale de Normalisation / Международная организация по стандартизации, 2011-02-07 [cit. 2014-05-16]. Kapitola Proposed Variation Sequences, s. 9–11. Dostupné v archivu pořízeném dne 2016-01-26. (anglicky)
