First off, why do you want to "summon" a demon? You should have REALLY good reason to work with a demon or any other kind of spirit. Second, many will tell you that "summoning" is not very ethical. Think of it like this. A demon is a spirit that has been in existence since creation. It is powerful, ethereal, and wise. It would be very arrogant of one to think that they could simply "summon" a demon to do their bidding. A more polite manner of spirit working is to invite or call the spirit. Ask for its wisdom and help. If it doesn't want to work with you then forget about it. I am sure that your will is not stronger than these beings'. I would advise you to gather more knowledge on spirit working and do some studying and research before attempting to work with any sort of spiritual being. Good luck and be safe.
Summoning what?Do you want to summon a goetia or a generic demon?If
you wanna summon goetia,Lesser Key Of Solomon Is the book you turn to.For other higher beings,the Higher Key is used.And keep Clevername's words in consideration.