@article {1793,
	title = {The Role of the Direction in Tissue P Systems with Cell Separation},
	journal = {Journal of Automata, Languages and Combinatorics},
	volume = { 19 (2014) 1{\textendash}4},
	year = {2014},
	pages = {185{\textendash}199},
	issn = {1430-189X},
	author = {Luis F. Mac{\'\i}as-Ramos and Miguel A. Mart{\'\i}nez-del-Amor and Mario J. P{\'e}rez-Jim{\'e}nez and Agust{\'\i}n Riscos-N{\'u}{\~n}ez and Luis Valencia-Cabrera}
}
