1. Aaronson S (1986) A role for algae as human food in antiquity. Food and Foodways 1:311–315
2. Adams DG, Duggan PS (1999) Heterocyst and akinete differentiation in cyanobacteria. New Phytol 144:3–33
3. Association of Official Analytical Chemistry - AOAC (1984) Official methods of analysis of the association of official analytical chemists,.14th edn. Arlington, USA, 1141p
4. Association of Official Analytical Chemistry - AOAC (1990) Official methods of analysis of the association of official analytical chemistsn 15th edn. Arlington, USA, pp 105–106
5. Bazzichelli G, Abdelahad N, Ventola F (1989) Structural modifications in the extracellular investment of Nostoc commune Vauch. during the life cycle. III. Macrocolonies. Arch Hydrobiol Suppl Algol Stud pp 365–370