Zinc potassium phosphate hexahydrate crystals for nonlinear opticsV. Krishnakumar, S. Manohar, R. Nagalakshmi, M. Piasecki, I. V. Kityk and P. BragielEur. Phys. J. Appl. Phys., 47 3 (2009) 30701DOI: https://doi.org/10.1051/epjap/2009094