1. Bumba, V., Do polar faculae terminate or commence an extended cycle of solar activity?, Astron. Inst. Czech. Bull., 1990, vol. 41, pp. 325–332.
2. Chistyakov, V.F., Metody issledovaniya Solntsa (Solar Research Methods), Vladivostok, 1986.
3. Li, K.J., Qiu, J., Su, T., et al., Periods of activity cycle of polar faculae, Publ. Astron. Soc. Jpn., 2004, vol. 56, pp. L49–L52.
4. Li, K.J., Liang, H.F., Gao, P.X., and Su, T.W., High- and low-latitude solar activities: Who leads whom in time phase?, Sol. Phys., 2006, vol. 236, pp. 185–197.
5. Makarov, V.I., Makarova, V.V., Polar faculae and sunspot cycles, Sol. Phys., 1996, vol. 163, pp. 267–289.