Free and Acylated Cholesterol in the Red Alga Gracilaria longa: Detection and Quantification by 1H- and 13C-NMR on Lipid Extracts - Toffanin, R; Murano, E; Modricky, C; Kvam, B J; Paoletti, S; Rizzo, R; Pollesello, P (Planta Medica, 1992)