I should also consider the date. Since Nickitin passed away in 1978, the copyright might have expired depending on country laws. But in many countries, copyright lasts for the author's lifetime plus 50-70 years. Assuming he died in 1978, the copyright might still be active or might vary by region. The paper should note that. Additionally, in the US, works published before 1923 are public domain, but Frol Nickitin's works would have been published later. Need to verify the exact copyright expiration dates for his specific works.