Plural of an initialism that ends with the letter S [duplicate]

Solution 1:

A search on Google for OSes returns results from several established websites such as infoworld.com, osnews.com and linux.com, which suggests OSes is the accepted form.

Solution 2:

I disagree with Antony Quinn's assertion that just because he can find relevant results by Googling OSes this justifies calling it "valid". I don't say Google Books is an ideal "arbitration tool", but it's a lot better than a simple Internet search. I searched for:

"OSs" unix windows linux 3120 written instances

"OSes" unix windows linux 1060 instances

"OS's" unix windows linux 520 instances

That's 3:1 in favour of the "regular form" (plurals of initialisms are formed by simply adding "s").

Solution 3:

When the word sounds like it ends in an "s" or "sh" (for example, witch /wɪtʃ/), you make it plural by adding "es."