ULTRASONIC ABSORPTION AND ORDER OF THE SMECTIC-A-NEMATIC PHASE TRANSITION R. BARTOLINO, F. SCUDIERI, D. SETTE et A. SLIVINSKIJ. Phys. Colloques, 36 C1 (1975) C1-121-C1-122DOI: https://doi.org/10.1051/jphyscol:1975122