1. Cauchy-Hadamard Theorem  
   Eric W. Weisstein, Wolfram Research Inc., Champaign, IL  
2. Ratio test  
   Wikipedia, the free encyclopedia  
3. Ratio Test  
   Eric W. Weisstein, Wolfram Research Inc., Champaign, IL  
4. Ratio test (Theorem)  
   PlanetMath.org  
5. Root test  
   Wikipedia, the free encyclopedia  
6. Root Test  
   Eric W. Weisstein, Wolfram Research Inc., Champaign, IL  
7. Cauchy's root test (Theorem)  
   PlanetMath.org  
8. Ratio and n-th Root Tests for Series   
   Robert C. Sharpley, Industrial Math. Institute, Univ. of South Carolina, Columbia, SC
9. Taylor Series - - d'Alembert  
   David M. Bressoud, Math. Dept., Macalester College, St. Paul, MN
10. Series of complex numbers  
    Noah Dana-Picard, Math. Dept., Jerusalem College of Technology, Israel
11. Convergence Tests   
    Bert G. Wachsmuth, Math. Deptl, Seton Hall University, South Orange, NJ
12. Ratio Test   
    Bert G. Wachsmuth, Math. Deptl, Seton Hall University, South Orange, NJ
13. Finding when Power Series Converge  
    Lawrence Neff Stout, Math. Dept., Illinois Wesleyan University, Bloomington, IL  
14. The Ratio Test  
    John Jones, Math. Dept., Arizona State University, Tempe, AZ
15. Radius of convergence  
    Marek Rychlik, Math. Dept., University of Arizona, Tucson, AZ
16. The Radius of Convergence  
    Aldrovando Luís Azeredo Araújo, Dept. de Matemática, Universidade Federal de Santa Catarina, Brasil
17. Ratio (and Root) Test   
    Beth Ruskai, Math. Dept., University of Massachusetts, Lowell, MA
18. The Root and Ratio Tests   
    Mohamed A. Khamsi, S.O.S. Mathematics, Paso, TX
19. D'Alembert's ratio test  PDF  
    Jonathan Robbins, Dept. of Engineering Mathematics, University of Bristol, UK
20. Power Series- Region of Convergence  PDF  
    Stephan R. Garcia, Math. Dept., University of California, Santa Barbara, CA
21. Absolute Convergence and the Ratio and Root Tests   PDF  
    Chris Cullop, Math. Dept., Kishwaukee College, Malta, IL
22. Infinite Series in Physics  PDF  
    John Shumway, Physics & Astronomy, Arizona State Univ., Tempe, AZ
23. Absolute convergence and ratio test  PDF  
    Mei-Qin Chen, Mathematics and Computer Science at The Citadel in Charleston, SC.

(c) John H. Mathews 2006