The Koran is what Mohammed said that the angel Gabriel said that Allah said. However, the Koran does not contain enough guidance for one to be a Muslim. The Koran repeatedly says that all the world should imitate Mohammed in every way.
Mohammed’s words and deeds are called the Sunna. The Sunna is found in two different texts— the Sira and the Hadith.
The first source of the Sunna is the Sira which is Mohammed’s biography. The most authoritative version is by Ibn Ishaq.
The other source of the Sunna is the Hadith, the Traditions of Mohammed. There are several versions of Hadith, but the most commonly used is by Bukhari.
So, the Trilogy is the Koran, the Sira and the Hadith.