Hi Pam, you might be interested to know part of the reason why you see different variations is that the original source is in Chinese and there are different systems of transliteration in order to convert the sound of the Chinese into Roman/Latin characters because the original Chinese characters are purely ideographic and have no pronunciation clues. There are different transliteration systems that have been used in the past couple of hundred years, and within each system the norms and conventions for when to combine the Roman characters (PanGu Pan Gu or Pangu, ShenGong or Shen Gong or Shengong, Tai Chi or Tai Ch'i or Taiji or Tai Ji) and when to split them up is not always consistent, just as there seems to be inconsistency in English when to capitalize the first letters of words in title or article names, etc. Just compare BBC articles on the web to the New York Times.
This kind of question comes up a lot when Chinese and English culture and language come into contact, and believe me you are definitely not the only person who ever wanted to know the exact, correct way to do something Chinese. Ha-hah! The same things also happen within China when different languages like Mandarin and Cantonese are in proximity, especially in regards to pronunciation of dialects not common to the local region.