how should one hyphenate this phrase?

with no hyphens:

"late nineteenth and early twentieth century thinkers"

MLA, AP stylebook and, presumably, the normal rules of grammar would say that you have to at least hyphenate centuries-- they're compound adjectives. So "twentieth-century thinkers." It is also common to use this construction: "mid- to late-twentieth century" in newspapers and academic writing. So I think there should also be a hyphen *and* a space at the end of "nineteenth." Should "late" and "early" be hyphenated to the numbers? Probably-- they're describing the part of the century, not the thinkers. So that would seem to result in

"late-nineteenth- and early-twentieth-century thinkers"

which looks atrocious. On the other hand, since most of these thinkers probably worked in *both* periods, maybe it should *all* be hyphenated

"late-nineteenth-and-early-twentieth-century thinkers"

but that also looks atrocious. This may be one one of those situations that is so egregious that we ought to abandon hyphens entirely (a la "peanut butter and jelly sandwich"). That or we should just write "thinkers in the late nineteenth and eary twenieth centuries." Harumph.