My uncle just finished 1.6 kg, 700 pages long dictionary of Northern Sami, a language spoken by around 20,000 speakers.
Sami are an indigenous people who have inhabited large parts of Northern Europe spanning from Russia to Norway for millenniums.
He has dedicated his life to advocate for their rights and preserve their languages and culture. This book is a major contribution in an effort to ensure that this ancient language will be passed on to future generations.