@book{29971,
	author = {Fagan, William, ed.},
	title = {Optical Security and Anticounterfeiting Systems},
	publisher = {SPIE},
	year = {1990 },
	series = {Proceedings of SPIE; V. 1210},
	address = {Washington, USA},
	url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/1210}
}