Do you know what's the name of this old horror movie? (from the 70's or the 80's)?

[sodomark]

It's about a demon that wants to posses a women (i think). I remember a scene where the women was tied down on a table (inside a library, or something like that) and the demon was smashing a metal door trying to get in. And a voice was telling the women to let him in.
In the scene above i remember seeing the demon getting thru the metal door and on top of the women (nothing else).
In the ending scene, the women is hugging her husband like everything it's ok but actually she is still possesd. You can see that in her eyes. It's similar to The Entity (1982). I'm trying to find these movie for years but still no succes!
I would really appreciate if someone could help me.