First Summoning Options

Two nights ago, I summoned my first entity. I didn't use a circle, or any other kind of protection. I just got into a trance, and I asked the nearest friendly entity to come forth. I felt him here, and I asked him his name. I'm not sure if it was my imagination, but
he told me his name was Apophis in a monster-ish kind of voice. I don't think it was my imagination... because if it was, I would've probably picked a name I could relate to... I've never heard of Apophis. Anyway, I asked him to leave, and I thought he did, until I got in bed to go to sleep, and I felt him behind me. He was touching my back or something. I banished him with the Solar Cross, and it worked. The end...

Greetings Traveller!
Well...I've read it in passing any number of times from Sumeria to Far Eastern Tibetan demonic-dieties references...
Here is one from the Sumerian:
http://www.stavacademy.co.uk/mimir/greatstag.htm
It doesn't have a diagram but rather mentions the Sumerian idea of the shape of the cosmos. In western tradition the circle is used to describe infinity. The Sumerians deemed that the square represented an aspect of the god Ea. It was also shown in the form of an equal armed cross (adopted by the Templars?). Another 'source' would be some of the yantra/mandalic diagrams which are used in the Simon Necronomicon.
http://iacmusic.com/symbolspage.html
Here is a site depicting many types of symbols and their various meanings.
I'm alittle flustered that I'm unable to point you in the direction of more comprehensive sourcing. It will show up when I least expect it. (IMG:style_emoticons/default/black eye.gif)