@article{napoli1999,
	author="M. Napoli and S. Zampieri",
	title="Two-Dimensional Proper Rational Matrices and Causal Input/Output Representations of Two-Dimensional Behavioral Systems",
	journal="Siam Journal on Control and Optimization",
	year="1999",
	pages="1538--1552",
	volume="37",
	issn="0363-0129"
}