R. C. Eckardt, H. Masuda, Y. X. Fan, and R. L. Byer, ��Absolute
  and relative nonlinear optical coefficients of KDP,
  KD*P, BaB2O4, LiIO3, MgO:LiNbO3, and KTP measured
  by phase-matched second-harmonic generation,�� IEEE J.
  Quantum Electron. 26, 922�933 (1990).
                  |  0     0    0   0    0.08   2.2 |
                d=| 2.2  -2.2   0  0.08   0      0  |
                  | 0.08  0.08  ?   0     0      0  |