Photoacoustic and optothermal studies of tomato ketchup adulterated by the red beet (Beta vulgaris) D. Bicanic, E. Westra, J. Seters, S. van Houten, D. Huberts, I. Colić-Barić, J. Cozijnsen et H. Boshoven J. Phys. IV France, 125 (2005) 807-810 DOI: 10.1051/jp4:2005125186