Probability and Statistics course in R:
http://www.math.bas.bg/statlab/tchorbadjieff/Undergraduates.html
with Assist. Prof. A. Tchorbadjieff
Probability and Statistics lecture notes and exercises in Bulgarian, hand-written:
https://drive.google.com/open?id=1AFd4HW7FRVzQFynoISoBW_LwJCfYcQuH
with Assist. Prof. E. Kamenov, Ph. D.