@book{9879,
	author = {Piaget, Jean},
	title = {La formación del símbolo en el niño :},
	publisher = {FCE,},
	year = {1961.},
	address = {México :},
	url = {https://drive.google.com/file/d/1JrbKj0XvlKaezeHGYpmUY4L9yR7MmX5D/view?usp=sharing}
}