ZAX, Jeffrey S. Introductory econometrics : intuition, proof and practice. Stanford : Stanford economics and finance, 2011. online [xxvii, 644 p.]. Available on Internet: <https://search.ebscohost.com/login.aspx?direct=true&db=nlebk&AN=362850&lang=sk&site=ehost-live&scope=site> ISBN 978-0-804-77720-9.