Oh, if the author just wrote DD.MM it's fine. I just don't understand why he wrote "June/July" afterwards.
It's Day/Month Day/Month
I'm from Poland (Europe)
Sure, but I think it's more that it seems incredibly rare to write month/day without year in strictly numbers. In almost all cases i would write 15 Jun/15 Jul. I can't think of anytime i would intentionally write 15.06/15.07. We all know this is a global world. We all know conventions vary. We should aim to make things intuitive, not make people guess which convention 06.07 is using.
Day.month is the standard throughout most of Europe.
And Latinoamérica.
"rare" is subjective - I'd have written it the same way (DD.MM) if I were going to write those dates without thinking. The author is from Poland, and so am I. Old habits die hard.