Drdla, Pavel, a Josef Bulíček. „FARE COLLECTION SYSTEM IN INTEGRATED PUBLIC PASSENGER TRANSPORT SYSTEMS". Perner’s Contacts 7, no. 2 (červenec 13, 2012): 22–33. Viděno duben 25, 2024. https://pernerscontacts.upce.cz/index.php/perner/article/view/1137.