@article {MR2985635,
	title = {On the permanence of predator-prey model with the {B}eddington-{D}e{A}ngelis functional response in periodic environment},
	journal = {Acta Math. Vietnam.},
	volume = {37},
	number = {2},
	year = {2012},
	pages = {267{\textendash}280},
	issn = {0251-4184},
	author = {Trinh Tuan Anh and Nguyen Huu Du and Tong Thanh Trung}
}
