I use the Key of Solomon to summon demons. The version I am using is the The Magical Treatise of Solomon a Greek version of the text. If you haven't read the Key of Solomon, I will give you a brief background.
There are two book in the Key of Solomon. The first book deals with summoning demons and spirits in order for them to obey the invoker. The second book deals with how the invoker should be clothed and purified before invoking the demons/spirits.
I have also used the Lemegeton or Lesser Key of Solomon to invoke demons. I also also used various diabolical signatures to compel demons to appear. When they have appeared it has usually been as noises, creaks, knocking or cold air as well as rancid smells.
I have also seen moving shadows on the walls, and this has been witnessed by friends who have helped invoke the demons and spirits. If you go to the demon page you will see a list of demons I have summoned in the order that I summoned them.