I don't know where this grammar point is treated in grammars by English authors. I have to look it up. In grammars by German authors this is treated in the chapter definite and indefinite article.
Normally the word order is article + adjective + noun. In special cases English uses a different order:
The definite article is in post-postion after all, both, double, half, quite, twice
all the children, both your hands, double the amount, quite the best film, half the loaf, twice the length
The indefinite article is in post-position after half, quite, rather, such, what (exclamation) as in
half a loaf (derived from: the half of a loaf), quite/rather a surprise,
What a man!
The indefinite article is in post-position when adjectives are modified by as ...as,
so, too, how, however as in
so difficult a task, too slow a run.
In the Longman Grammar of English by L.G. Alexander you find it only by using the register (too clever a man) and he has only one example and does not give a survey about this grammar point.
I have never seen a name for structures of the type "so young a girl", but I would put it in the box "special positions of adjectives".