books similar to movies?

My friend is looking for horror books with similar subject matter as The Exorcist and The Last House on the Left. Recommendations would be appreciated.

It might be obvious, but has your friend read the Exorcist? There's also Blatty's follow-up: Legion

Michael Laimo has a novel called The Demonologist about a possessed rock star.

As for The Last House on the Left, your friend might like The Woods Are Dark or Off Season? or possibly Dean Koontz Intensity?

#1 & #2

I second jseger9000's recommendation to read The Exorcist novel. I found it much more frightening than the film.

Although I haven't read it, Jack Ketchum's The Girl Next Door may be a good recommendation on The Last House on the Left subject matter.

She told me she's read The Exorcist and that she likes fiction horror books so long as they deal with realistic situations. She believes in ghosts and all, so to her that would be considered realistic.
Thanks for the recommendations.

The Haunting of Hill House and (if you can find it) The Edge of Running Water.

Both were made into movies; the books were better.