Hi,
Here is a start:

Circuit Cellar Magazine
http://www.circuitcellar.com/

Choosing the Right Crystal For Your Oscillator
http://www.circuitcellar.com/library...os91/index.htm

Circuit Cellar>Selecting quartz crystals for oscillators can be confusing and mysterious.

Four crystal parameters play a key role in system accuracy. The contribution from each must be added to obtain the total system accuracy....

Frequency tolerance....
Frequency stability is a function of temperature and is related to the crystal cut type.
Aging...
Load capacitance....