Question: In the sentence

> 
> I have a bibliography page which I'd like to **split in/into** sections
> 
> 
> 

which would you rather use: *split in* or *split into*?

Why?

Answer: 
There's not really a "grammatical" justification for the choice, but idiomatically, we [almost always](http://books.google.com/ngrams/graph?content=split%20in%20sections,split%20into%20sections&year_start=1700&year_end=2000&corpus=0&smoothing=3) use *"into"* with *"sections"*...

![enter image description here](https://i.stack.imgur.com/1n8Dv.png)

...whereas with *"half"*, for example (there aren't many such examples), it's [the other way around](http://books.google.com/ngrams/graph?content=split%20in%20half,split%20into%20half&year_start=1700&year_end=2000&corpus=0&smoothing=3)

![enter image description here](https://i.stack.imgur.com/WAkM8.png)

In fact, apart from *"half"* I'm not sure there's any other split you can make where *"into"* isn't preferred. If you compare [split in/into two](http://books.google.com/ngrams/graph?content=split%20in%20two,split%20into%20two&year_start=1700&year_end=2000&corpus=0&smoothing=3), the preference isn't quite so marked - but that's probably influenced by the unusual usage with *"half"*. As you go to bigger numbers, the preference for *"into"* [is overwhelmingly reasserted](http://books.google.com/ngrams/graph?content=split%20in%20three,split%20into%20three&year_start=1700&year_end=2000&corpus=0&smoothing=3).

For a (weak) justification of the idiomatic preference for *split **into*** over *split **in***, I suggest that in numerous "compound verbs" *(lapse into a coma, descend into chaos, developed into full-blown AIDS, etc.)*, the *"into"* component strongly associates with "transformation" of the primary subject.

That association very much involves the "sub-component *"to"*, which can pass muster on its own in things like *turn to stone, bring to focus, etc.*. With those, you can get away with *"into"*, but you couldn't possibly use *"in"*.
Split in sections does not make any sense - you would have to split something **into** sections.