Mosolov's Piano Sonata No. 1 accidentals

[johnflans128]

So, to get straight to the point, the accidentals in this piece are whack. Every time I think there's a pattern it's lost in the next measure. You can find the sheet music's first page anywhere, just look it up, but I'm wondering if there's a pattern and I just don't get it. One minute a note, at the start of a measure, has a natural (just to make sure the player doesn't think it's sharped) but then the natural sign is left out for other notes. Specifically on measure 20 there are two notes (a sharped f and a sharped g) and at the end of the measure the notes appear again, yet in many recordings I've heard them played as naturals (even though there is no indication they are). Please help, thanks.