@book{68023,
	author = {Ashraf Mohamed Abdelhaleem and Fawzya Mohamed Tayel , },
	title = {Limiting efficiency and simulation of the graded bandgap solar cell / },
	publisher = {Ashraf Mohamed Abdelhaleem , },
	year = {2003},
	address = {Cairo : },
	url = {http://172.23.153.220/th.pdf}
}