@book{24575,
	author = {Ertel, Suitbert},
	title = {Factor analysis},
	url = {https://library.oapen.org/bitstream/20.500.12657/37035/1/Ertel_factor.pdf||https://library.oapen.org/bitstream/20.500.12657/37035/1/Ertel_factor.pdf}
}