I seem to remember the old askoxford.com site said either was acceptable: CDs and CD's.
But now the replacement Oxford Dictionaries Online firmly suggests to avoid the apostrophe except in a few special cases:
Apostrophes and plural forms
The general rule is that you should not use an apostrophe to form the plurals
of nouns, abbreviations, or ...
As the doctor also has an appointment with you, doctor's appointment is appropriate in its own right. It is also by far the most common as a set phrase:
Any other plural usage would be entirely subjective.
Graph source: Google Books Ngram
The most useful rule — and the most general and the easiest to remember — is simply that you add ’s whenever you actually say an extra /əz/ at the end when forming the possessive, compared with how you say the non-possessive version. Let your own ear be your guide. That’s all there is to it. No fancy rules full of exceptions. Just your own ear (as a native ...
The fourth example is the correct interpretation of day's, but with two things to keep in mind.
First, in your conclusion you flipped the words around incorrectly*; the journey "belongs to" the day, not the other way around. You could re-write the sentence as:
The house is a journey of a full day from here.
Second, while the journey is "of a day," this ...
In The New Fowler's Modern English Usage, the late Burchfield offered a guide to the use of possessive s and of with inanimate nouns. It is the most comprehensive and well founded stylistic advice I could find on the subject. He had worked on the Oxford English Dictionary and knew a lot about language and style. A summary:
A noun that is possessive or ...
It's called a "transferred epithet"- the possessive case is incidental, as in...
I had a good night's sleep: The good sleep was mine to enjoy, but it is attributed to the night it happened.
He put in a honest day's work: The quality or extent of work belonged to the doer, but it is attributed to the day.
The answer lies in the history of how apostrophes have been used, and how this has then changed:
A Brief, but not that Brief, History of the Apostrophe in English
There’s a myth that the apostrophe is only used for elision. It’s a pretty useful myth, because believing it is unlikely to lead you into mistakes if you are using the most popular styles today, ...
The apostrophe indicates possession.
Without an apostrophe you are indicating plurality.
Since the point you are trying to convey is that the assumption you made yesterday is no longer valid, the apostrophe is appropriate.
Yesterday's assumption is no longer valid.
It's kind of like saying "The assumption of yesterday".
The Chicago Manual of Style says:
Capital letters used as words, numerals used as nouns, and abbreviations usually form the plural by adding s. To aid comprehension, lowercase letters form the plural with an apostrophe and an s.
The lowercase letter exception presumably exists because omitting the apostrophe can make the sentence much harder to understand (...
I think the arguments on that site are pretty weak.
For one, the argument that "If you can't think of an example, there mustn't be one" is very poor. A lack of imagination does not constitute a robust argument.
In addition, the writer suggests replacing the pluralising 's' with a 'z', to get over the problem of singular and plural possessives. So, he's ...
I agree with Wikipedia, wordreference and CMOS - acronyms and initialisms are "regular" nouns; plurals are formed by adding "s".
Checking Google Books for actual usage in a relatively "contentious" case, I searched for:
"OSs" unix windows linux 3120 written instances
"OSes" unix windows linux 1060 instances
"OS's" unix windows linux 520 ...
As few people are addressing the '"more scientific™" sources' bit of the question, it should be pointed out that there are a number of English style guides out there, practically all of which should cover the topic of forming possessives with apostrophe-s (as it's a frequent issue even with native speakers).
You should be able to find copies of at least one ...
It doesn't matter how many different authorities/style guides are cited - usage in this area has never been fixed, so it doesn't mean much to suggest the "rule has changed over time".
The use of apostrophes has always been less common, but it's been around at least a century (there, for example, the 1700's). It's also worth noting that (particularly in ...
There are a few limited cases for which an apostrophe is not used to indicate possession. For example, if you're referring to something belonging to it or her, the correct form is its or hers, with no apostrophe.
Such an exception does not apply to column. If you want to refer to the width of a particular column, you would say the column's width. In the ...
The difference is in the number of users.
User's guide: A guide belonging to one user.
Users' guide: A guide belonging to all the users.
I'd be inclined to use the first sense rather than the second sense, since the "one" user is really an abstract representation of all the users anyway.
Because the dozen isn't the collective property of all bakers, but of a generic baker. It's the same reason it's a carpenter's square, a driver's license, or a greengrocer's apostrophe.
You see both farmer's market and farmers' market because there are several farmers selling at a farmers' market, so you can also think of it as a market that collectively ...
The strongest endorsement that I could find from a UK English source in favor of using 's after singular nouns of any kind to indicate possession is this brief treatment from The Oxford Guide to Style (Oxford University Press, 2002):
Use 's after singular nouns and indefinite pronouns that do not end in s:
[Examples:] the boy's ...
A piece of advice here from someone who did a CS Master's thesis himself:
You don't. You write it the way they want it written. Consider it like a house style guide. The rules in style guides aren't the only way to do proper English; just the way they do it there. Your goal here is to get a CS Master's, not a Booker Prize.
Look at it this way: Your advisor ...
An easy way to differentiate:
An apostrophe is only used within or at the very end of a word - it is part of the word.
In English, it serves three purposes:
The marking of the omission of one or more letters (as in the contraction of do not to don't).
The marking of possessive case (as in the cat's whiskers).
The marking as plural of written ...
My answer focuses on the header question about decades—which is the question that most readers will probably expect to find answers to here. With regard to decades expressed in numerals rather than spelled out in letters, some style guides recommend omitting an apostrophe, while others recommend including it. For example, from The Chicago Manual of Style, ...
The following nGram suggests that dos and donts, do's and don'ts, and do's and don't's are all used, but it appears that do's and don'ts takes the cake.
A quick search suggested that capitalizing all but the s is also fairly popular:
DO's and DON'Ts
From Charles Darwin's Origin of Species
OR THE PRESERVATION OF FAVOURED RACES IN THE STRUGGLE FOR LIFE.
From the First Edition, 1859
One of the most remarkable features in our domesticated races is that we see in them adaptation, not indeed to the animal's or plant's own good, but to man's use or fancy.
How fleeting are the wishes and efforts of ...
T. O. Churchill, A Grammar of the English Language (1823) identifies two somewhat surprising culprits as being responsible for the deplorable rise of the apostropheless its: printers, and English speakers who inexcusably use of the wrong contraction for "it is." Here is Churchill's argument:
The word it's in particular, is now generally robbed of the ...
It would depend on what you meant. If you mean the Brazilian army was short of ammunition, then you would write the Brazilian Army's ammo supply is low.
But if you were referring to an army that is not the Brazilian army, but instead owned or run by a particular Brazilian (perhaps an army of toy soldiers, or an army of mercenaries), then the Brazilian's ...