Good substitutes for Ross's book on Probability Models I was wondering if there are any **FREE** good alternatives to Sheldon Ross's Probability Models which are more succinct? Are there any free online resources (websites/PDFs/course notes) which cover more or less the same material? I am looking for a quick (review)/(filling of knowledge gaps) and therefore would appreciate brevity.

how about this one from Oliver Knill's page at Harvard: <