@article {Castro:31 January 2000:0020-0190:11,
	author = "Castro J.",
	author = "Guijarro D.",
	title = "PACS, simple-PAC and query learning",
	journal = "Information Processing Letters",
	volume = "73",
	year = "31 January 2000",
	abstract = "",
	pages = "11-16(6)",
	url = "http://www.ingentaconnect.com/content/els/00200190/2000/00000073/00000001/art00161"
	doi = "doi:10.1016/S0020-0190(99)00161-1"
}