Alonso-Fernandez, Fernando; Bigun, Josef: 'An overview of periocular biometrics' (Security, 2017), 'Iris and Periocular Biometric Recognition', Chap. 2, pp. 29-53, DOI: 10.1049/PBSE005E_ch2
IET Digital Library, https://digital-library.theiet.org/;jsessionid=dn7wln3v1941.x-iet-live-01content/books/10.1049/pbse005e_ch2