1. Adams DG (1992) Multicellularity in cyanobacteria. In: Mohan S, Dow C and Cole JA, (eds) Prokaryotic Structure and Function: A New Perspective, pp 341–384. Cambridge University Press
2. Armstrong RE, Hayes PK and Walsby AE (1983) Gas vacuole formation in hormogonia of Nostoc muscorum. J Gen Microbiol 128: 263–270
3. Balkwill DL, Nierzwicki-Bauer SA and Stevens SE Jr (1984) Modes of cell division and branch formation in the morphogenesis of the cyanobacterium Mastigocladus laminosus. J Gen Microbiol 130: 2079–2088
4. Bergman B, Johansson C and Söderbäck E (1992) Transley Review No. 42 — The Nostoc-Gunnera symbiosis. New Phytol 122: 379–400
5. Bonnett HT and Silvester WB (1981) Specificity in the Gunnera-Nostoc endosymbiosis. New Phytol 89: 121–128