Wikipedia
Al Ghadir (that is " The Ghadir in the Book, the Sunnah, and Literature") is a 20-volume book written by the Iranian Shia scholar Abd Al Husayn Amini.
The main subject of this book is discussing Hadith of the pond of Khumm according to Sunni documents. In order to do so, Amini has gathered the narrations of 110 companions ( Sahaba) as well as 40 followers of Muhammad about the event. He then states the related Hadiths narrated by 360 Hadit narrators between 2nd to 14th centuries of Islamic calendar. Since Sunni Muslims - unlike Shia Muslims - do not consider Ali as the immediate legitimate successor of Muhammad, Amini in his book has tried to prove Ali's succession based on Sunni documents. Amini, in writing the book, traveled to different countries in order to take advantage of the libraries there among which were India, Iraq, Pakistan, Morocco, Egypt and some others.
The first print of Al-Ghadir book published in Najaf City and developed by 9 volumes. After publishing of this great book, most of scholars of different Islamic countries wrote an explanation on it.