@book{55776,
	author = {Bettelheim , Charles },
	title = {Some Basic Planning Problems /},
	publisher = {Indian Statistical Institute ,},
	year = {1961 .},
	series = {Indian Statistical Series},
	address = {Bombay :},
	url = {https://fll.law.cu.edu.eg/fulltext/bks/B13-09324.pdf}
}