Texas Instruments
Texas Instruments: The Derivative as a Limit
Read about the near-simultaneous discovery of Calculus by Liebniz and Newton, then see some examples worked through of finding derivatives of functions using the limit definition of derivative. Following the examples are exercises with...
Wolfram Research
Wolfram Math World: Leibniz Criterion
This page states the Leibniz Criterion, or the alternating series test that determines whether or not an alternating series converges.