IBRAHIM, R., PLECHÁČ, P. Frequency of parts of speech in Adolf Heyduk’s poetry. In: KUBÍČEK, T., LASS, A., eds. Roman O. Jakobson: a work in progress. Olomouc: Palacký University, 2014, s. 133-144. ISBN 978-80-244-4386-7. Dostupné z: http://versologie.cz/v2/pdf/papers/ripp2014jakobson.pdf