I'm having a hard time understanding the phrasing 'Certain of the rules'.

So I googled it. There I found the following sentences:

  • By certain of the Rules as we have seen they are a special fund applicable in priority to certain kinds of debts.

  • But English is descended from an ancestral German dialect, not from Latin, and certain of the rules based on Latin grammar simply do not fit the structure of English.

  • I may mention that certain of the rules which we have laid before the Privy Council
But I'm still struggling to understand its meaning or how to use it. Please help.
Certain of the rules = some of the rules
Mister MicawberCertain of the rules = some of the rules
Ah, right. Thanks, I also just found the meaning in a dictionary. Says it's reserved for formal writing. I think I might just stick with 'some.'