@InCollection{LU2008a, author = {Pawe{\l} {\L}upkowski and Mariusz Urba\'{n}ski}, title = {SemCAPTCHA. Telling Computers and Humans Apart by Means of Linguistic Competence and Positive Semantic Priming}, booktitle = {Computational Intelligence: Methods and Applications}, pages = {525--531}, publisher = {Academic Publishing House EXIT}, year = {2008}, editor = {L. Rutkowski and R. Tadeusiewicz and L. A. Zadeh and J. Zurada}, address = {Warszawa}, }