Cita APA (7a ed.)
Liu, Y. COVID-19: Prevention Guideline. Smashwords.
Cita estilo Chicago (17a ed.)
Liu, Yiqing. COVID-19: Prevention Guideline. Monterey, EUA: Smashwords.
Cita MLA (9a ed.)
Liu, Yiqing. COVID-19: Prevention Guideline. Smashwords.
Precaución: Estas citas no son 100% exactas.