KAMPF, Rudolf et al. Motivation level and its comparison between senior managers and blue-collar workers in small and medium-sized transport enterprises. In Communications : scientific letters of the University of Žilina. ISSN 1335-4205, 2017, vol. 19, no. 4, p. 43-49. VEGA 1/0024/17 ; APVV-16-0297. SCOPUS. Dostupné na internete: <https://komunikacie.uniza.sk/magno/csl/2017/mn4.php>