References
- Hogg , Robert V. and Tanis , Elliot A. 1977 . Probability and Statistical Inference , New York : Macmillan .
- Johnson , Richard E. , Koikemeister , Fred L. and Wolk , Elliot S. 1978 . Calculus With Analytic Geometry, , 6th ed. , Boston : Allyn and Bacon .