1. 2) Cagauan, A. and S. V. Pullin 1994. Azolla in Aquaculture: Past, present and future. In “Recent Advances in Aquaculture” Vol. 5. ed. by J. T. Muir, and R. J. Roberts, Blackwell Science, Cambridge, pp. 104-130.
2. 4) Dao, T. T. and Q. T. Tran 1979. Use of Azolla in rice production in Vietnam. In “Nitrogen and Rice” IRRI, Phillippines, pp. 395-405.
3. Sexual hybridization among Azolla species