Guru Shabad Ratnakar Mahan Kosh (Punjabi: ਗੁਰਸ਼ਬਦ ਰਤਨਾਕਰ ਮਹਾਨ ਕੋਸ਼), known by its more popular name of Mahan Kosh (ਮਹਾਨ ਕੋਸ਼) and by the English title Encyclopædia of the Sikh Literature, is a Punjabi language encyclopedia which was compiled by Bhai Kahn Singh Nabha over fourteen years. It was the first Punjabi encyclopedia, it contains more than 70,000 words, some of them has sufficient reference from Guru Granth Sahib, Dasam Granth, Gur Pratap Suraj Granth and from other Sikh books. It is considered a groundbreaking work in terms of its impact and its level of scholarship. Source: Wikipedia (en)