Fatigue Crack Growth Behavior of Silicon Nitride: Roles of Grain Aspect Ratio and Intergranular Film Composition, 
Greene, R. B., Fuenfschilling S., Fett T., Hoffmann M. J., and Kruzic J. J. 
, Journal of the American Ceramic Society, Jan, Volume 96, Number 1, p.259-265, (2013)