• Investigation of the conductivity stability of doped polyparaphenyleneGolovtsov, Igor; Öpik, Andres24th Estonian Chemistry Days : abstracts of scientific conference1998 / p. 18
  • Temperature dependence of conductivity for polyparaphenyleneÖpik, Andres; Nirk, Tiit; Kerm, Karin; Golovtsov, IgorKemia-kemi = [Finnish chemistry]1991 / p. 985 https://www.ester.ee/record=b1201067*est
  • The kinetics of high temperature doping of the polyparaphenyleneGolovtsov, Igor; Öpik, AndresTallinna Tehnikaülikooli Toimetised1994 / lk. 35-48: ill
  • Исследование концентрации носителей легированного галогенами полипарафениленаÖpik, AndresЭлектронные материалы1989 / с. 30-40