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He scored two victories in April 1917 , both on 13 April , when he downed ( along with Lieutenant Donat Makeenok and Ensign Vasili Yanchenko , the latter being Russia 's second highest-scoring ace of the war ) two Hansa-Brandenburg C.I aircraft .
 person: Donat Makeenok; person: Vasili Yanchenko
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: Donat Makeenok; person: Vasili Yanchenko