@book{2018,
	author = { Sobel, Max A.},
	title = {Algebra and trigonometry .- 5th ed.  / Max A. Sobel, Norbert Lerner.},
	publisher = {Englewood Cliffs, NJ : Prentice Hall, c1995},
	address = {Englewood Cliffs, NJ : Prentice Hall, c1995}
}