[1] www.eurojournals.com/ejsr.htm
[2] http://www.academicjournals.org/IJPS/
[3] www.rmz-mg.com/letniki/rmz52/rmz52_0127-0130.pdf
[4] www.rmz-mg.com/letniki/rmz52/rmz52_0123-0126.pdf
[5] www.japenvs.4T.com
[6] www.sciencefocusngr.org