olemustõenäosusteoorias:üheainsa tulemiga sündmus ülevaateidhttps://libraryguides.centennialcollege.ca/c.php?g=717168&p=5125562https://mathbitsnotebook.com/Algebra2/Probability/PBCompoundEvents.htmlhttps://www.nagwa.com/en/explainers/985161036067/