Furmańczyk, Konrad, i Stanisław Jaworski. 2012. „Unemployment Rate for Various Countries since 2005 to 2012: Comparison of Its Level and Pace Using Functional Principal Component Analysis”. Metody Ilościowe W Badaniach Ekonomicznych 13 (2):40-47. https://qme.sggw.edu.pl/article/view/3534.