See: here
For example Integral representations AiryAi[z] is :
AiryAi[z] == (1/Pi) Integrate[Cos[t^3/3 + z t], {t, 0, Infinity}] /; Im[z] == 0
Or use this commands:
MathematicalFunctionData["AiryAi", "SeriesRepresentations"]
MathematicalFunctionData["AiryAi", "IntegralRepresentations"]
MathematicalFunctionData["AiryAi", "LimitRepresentations"]
MathematicalFunctionData["AiryAi", "AlternativeRepresentations"]
Regards M.I.