VILHELM, Daniel. Niektoré prístupy k tieňovej ekonomike. In Management challenges in the 21st century : managing the intangible: ethics and value changes in business, education and research : conference proceedings : [5th international research conference] : april 25, 2013, Bratislava. - Bratislava : [School of Management/Vysoká škola manažmentu v Trenčíne], 2013. ISBN 978-80-89306-20-6, s. 110-130. Available on Internet: <http://www.cutn.sk/Library/proceedings/mch_2013/editovane_prispevky/14.Vilhelm.pdf>