NON-LINEAR OPTICAL PROPERTIES OF A NEW ORGANIC-INORGANIC CRYSTAL : 2-AMINO-5-NITRO-PYRIDINIUM-DIHYDROGEN-PHOSPHATE (2A5NPDP) Z. KOTLER, R. HIERLE, D. JOSSE, J. ZYSS et R. MASSE J. Phys. IV France, 01 C7 (1991) C7-785 DOI: 10.1051/jp4:19917212