POLCYN, Jan.
 Information about No 5 (2017).
<strong>Progress in Economic Sciences</strong>, [S.l.], n. 5, apr. 2019.
ISSN 2391-5951.
Available at: &lt;<a href="https://pes.ans.pila.pl/index.php/PES/article/view/181" target="_new">https://pes.ans.pila.pl/index.php/PES/article/view/181</a>&gt;. Date accessed: 25 may 2026.