Strictly speaking the capacitors should be chosen to match the load capacitance the crystal is cut for.
CL = (CL1 * CL2) / (CL1 + CL2) + CS
CL1 = CL2 = 2 * (CL - CS)
The crystal spec seems to implie they are designed for 30pf caps
the item on the on-line suppliers site I'll probably be using is here