@book{42659,
	author = {Youssef, N. S. and Awad, EI. M. M.},
	title = {Effect of calcium sources on yield, aulity and development of dry and soft rot diseases on some potato varieties},
	url = {http://nile.enal.sci.eg/EALE/2006/MUJAS/3106/6/3801.pdf}
}