APA (7th ed.) Citation

Serzhuk, O. P., & Opalko, A. I. (2015). Genus of Crataegus L. in Ukraine.

Chicago Style (17th ed.) Citation

Serzhuk, O. P., and A. I. Opalko. Genus of Crataegus L. in Ukraine. 2015.

MLA (8th ed.) Citation

Serzhuk, O. P., and A. I. Opalko. Genus of Crataegus L. in Ukraine. 2015.

Warning: These citations may not always be 100% accurate.