The Tripitaka, also known as Pipitaka, is the earliest collection of Buddhist writings. Initially these writings were composed orally and passed down by traditional teaching and re-telling. By the Third Century B.C., they were written in the language of the monks, called Pali. Tripitaka means literally "the three baskets" deriving from the word "tri" (three) and "pitaka" (baskets). This refers to the way in which the texts were written on long, narrow leaves and sewn together at one side, almost like a book binding. They were then stored in bunches in baskets. The modern edition of these writings has forty-five volumes.
Vajrayana Buddhism draws upon many other Buddhist writings for its influences. It reveres the Tripitaka, the very first Buddhist text that was translated into Tibetan. It also leans heavily on the writing of Nagarjuna, an early Buddhist thinker, and his followers, as well as the Mahanya Sutras on Wisdom. Vajrayana also draws from many Tantric texts and writings about them.
Another source of Buddhist texts are the works of Buddhist monks themselves who wrote as they studied the texts that had gone before them. In the West, we are still unfamiliar with the majority of these but two are well known; Te Tibetan Book Of The Dead sets out the stages that a person will go through whilst they are dying, at the time of their death, when first deceased, and finally preparing for and finally achieving rebirth. At each of these stages other texts are read to the person who has died and if their soul hears and correctly interprets what is being read to them, they are able to achieve Nirvana without rebirth.
The Great Stages of Enlightenment is another text that has become familiar in the Western world. Written by a Buddhist philosopher and monk called Tsongkhapa, it explains the importance of ethical behavior and mind control as a prerequisite of correctly engaging in Tantric practice.