Apostrophe with conjunction [duplicate]
Wikipedia has this:
Joint or separate possession
For two nouns (or noun phrases) joined by and, there are several ways of expressing possession, including:
- marking of the last noun (e.g. "Jack and Jill's children")
- marking of both nouns (e.g. "Jack's and Jill's children").
Some grammars make no distinction in meaning between the two forms. Some publishers' style guides, however, make a distinction, assigning the "segregatory" (or "distributive") meaning to the form "John's and Mary's" and the "combinatorial" (or "joint") meaning to the form "John and Mary's". A third alternative is a construction of the form "Jack's children and Jill's", which is always distributive, i.e. it designates the combined set of Jack's children and Jill's children.
When a coordinate possessive construction has two personal pronouns, the normal possessive inflection is used, and there is no apostrophe (e.g. "his and her children"). The issue of the use of the apostrophe arises when the coordinate construction includes a noun (phrase) and a pronoun. In this case, the inflection of only the last item may sometimes be, at least marginally, acceptable ("you and your spouse's bank account"). The inflection of both is normally preferred (e.g. Jack's and your dogs), but there is a tendency to avoid this construction, too, in favour of a construction that does not use a coordinate possessive (e.g. by using "Jack's letters and yours"). Where a construction like "Jack's and your dogs" is used, the interpretation is usually "segregatory" (i.e. not joint possession).
("General principles for the possessive apostrophe", in "Apostrophe")
So in your example, unless they are writings that Giovanni and Walker co-wrote, you should use Nikki Giovanni's and Alice Walker's writings. Although I agree that it trips off the tongue better with just the second 's, and no doubt only the pedants in the audience would pick you up on it ;)
If in doubt, reword.
There will be readings from the writings of Nikki Giovanni and Alice Walker.
Written English is often (usually?) slightly more formal than spoken English. So of the two choices you offer, I'd write the first. This is mostly because I regard it as correct English.
The advice here is good, better than what you will generally find for this question. The convention seems to be that, for a joint item (combinatorial) with proper nouns (names of people), putting an apostrophe at the end of the combination is best whereas for other cases, both should get an apostrophe. Thus, "Jack and Jill's bucket" but the "writers' and editors' wages". Some suggest that the latter is correct only if the target item (the wages) is actually a multiple/separate form (so the writers have wages and the editors have wages). I disagree, and think this is generally less clear.
Consider "John and Jill's dogs are friendly". The general argument found around the web and in, it seems, many publication guides, is that this will be interpreted as the dogs of John and Jill are friendly. But a strict reading of it says that John is friendly and Jill's dogs are friendly. Indeed, if the latter meaning was what was intended, it would be written the same way (unless the sentence is completely restructured). This weakens the value of the apostrophe in indicating possession.
A different case may help. If I want to say that the teacher was talking to me, and also to John, I would say that the teacher was teaching to John and me. The way to teach kids to get this right (and thus not say 'I') is to take out John and just have it for me. The correct form is now easier to see for kids. The rule here is that the sentence should work if just for "me".
The same logic should be applied to apostrophes. "John's and Jill's dogs" holds true for this approach, but "John and Jill's dogs" doesn't. There is no ambiguity in the former, aside from whether the dogs are co-owned or separate dogs. However, I would argue that conveying this latter information is not the job of the conjunctive structure/use of the apostrophe. That is, the apostrophe should indicate possession. If that leads to ambiguity on whether the target is a singular shared target or separate targets, then that needs to be corrected in some other way. It is unlikely that you would have a problem using the apostrophe this way, though, as context is likely to have already conveyed the nature of the target. Whereas the approach of just putting an apostrophe at the end of the joint pairing (John and Jill) does create ambiguity because there are plenty of cases where context will not make it clear that it is a pair.
I think publication guides lean toward "John and Jill's conclusion" is because they are actually personifying a manuscript. That is, what is often being said in a manuscript is "the conclusion in the manuscript by John and Jill...", and the short-hand becomes the "John and Jill's conclusion" because the sense is that the conclusion belongs to the manuscript (referred to in manuscripts as John and Jill), not to John and Jill the people. That is technically wrong, but the alternative is more wordy and can feel clunky. But it seems to have led to the guides being used as writing bibles and a special case corrupting general use.