@book{894,
	author = {Jennison, Christopher, and Turnbull, Bruce W },
	title = {Group sequential methods with applications to clinical trials },
	publisher = {Chapman & Hall/CRC,},
	year = {c2000.  },
	address = {Boca Raton},
	url = {http://www.statsnetbase.com/ejournals/books/book%5Fsummary/summary.asp?id=639}
}