Feller William. An Introduction to Probability Theory and its Applications. Volume 1

2nd ed. — N.Y.: John Wiley & Sons Inc., 1957. — 462 p.The favorable reception of the first edition surpassed the most daring anticipation and, in addition to an unexpected number of users, the book seems to have found friends who read it merely for fun; it is most heartening that they range from pure mathematicians to pure amateurs. Although I cannot here express individual thanks to all readers to whom I am indebted for useful critical comments, their communications stimulated me during six years to think of improvements and to collect better examples and exercises. I hope that these will make for easier reading and teaching from the book.