Research into the death of Feliks Sienkiewicz (or Senkiewicz)

[Baptiste_R]

(I am French, I am writing in English for better understanding)

Hello, I would like to know if you could help me find the date of death of a certain Feliks Sienkiewicz, one of my ancestors? I know he was born in Praszka in 1887, married there in 1908, and had children. I know he died between 1914 and 1921 (the year of his wife's death, who is listed as a widow), but I can find no record of his death within that period.
If you can't help me, that's okay, I understand.

I wish you a good day.

Sincerely,

Baptiste