1. Response of Azolla to P. K and Zn in different wetland rice soils in relation to chemistry of floodwater;S. Ali;Soil Sci. Plant Nutr.,1986
2. Growth and nitrogen fixation of Azolla mexicana plant affected by NPK levels;A. Nasser;Bull. Fac. Sci. Alexandria Univ.,1995
3. Azolla: A green gold mine with diversified applications;A. Ahluwalia;Indian Fern J.,2002
4. Light and phosphorus interaction on growth, nitrogen fixation and mineralization of Azolla pinnata;A. Alejar;Phil. J. Sci.,1985
5. Microdetermination of phosphorus;P. Chen;Anal. Chem.,1956