Stock, J.H. and Watson, M.W. (2020) Introduction to econometrics. Fourth edition. Harlow, United Kingdom: Pearson Education Limited. Available at: https://bibliu.com/users/saml/samlUCL?RelayState=eyJjdXN0b21fbGF1bmNoX3VybCI6IiMvdmlldy9ib29rcy85NzgxMjkyMjY0NTIzL3BkZjJodG1sZXgvaW5kZXguaHRtbCJ9.