$^{137}$Cs Adsorption-Desorption Processes in Sediments, Using Gamma Ray Spectroscopy - Mertzimekis, T. J.; Ioannides, K.G.; Papachristodoulou, C.A.; Karamanis, D.T.; Stamoulis, K.C. (Advances in Nuclear Physics, Proceeding of the 6th Panhellenic Symposium of the Hellenic Nuclear Society, 1995)