@book{672,
	author = {Gamma, Erich and Helm, Richard},
	title = {Design patterns: elements of reusable object-oriented software},
	publisher = {Addison-Wesley,},
	year = {1995},
	address = {Indianapolis, USA :},
	url = {https://itmsp.museknowledge.com/UOH?qurl=https://libros-uoh.uoh.cl/ESCUELADEINGENIERIA/INGENIERIA%2520CIVIL%2520EN%2520COMPUTACION/Design-Patterns-Elements-of-Reusable-Object-Oriented-Software}
}