@book{29973,
	author = {van Renesse, Rudolf, ed.},
	title = {Optical Security and Counterfeit Deterrence Techniques II},
	publisher = {SPIE},
	year = {1998 },
	series = {Proceedings of SPIE; V. 3314},
	address = {Washington, USA},
	url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/3314}
}