Which novels does the Bungaku Shoujo movie cover? I would like to watch the Bungaku Shoujo movie at some point, but I don't want spoilers for the novels. Skimming over the Wikipedia page, it seems that some events haven't happened yet as of the end of the fourth novel, while other events seem to correspond to earlier novels. There may be other spoilers, some of them major, and that also makes me afraid to research this topic too deeply on my own.

Which novels provide the major plot points for the movie? Please use spoiler tags as appropriate.
I've read the first 5 novels and from what I see, the main plot of the movie is basically the 5th novel (which is also the thickest one), though there are some parts of the other novels in there too, especially in the beginning and in the end (after the scene in the planetarium).