Fourth volume of Mongolian Grammar written by academician B. Rinchen in 1967 and named Syntax is one of the biggest works on Mongolian linguistics and literature. The main direction of this work is the study of compound words in Mongolian language. B. Rinchen presented the principles as follows: a) Phonetics and phonemics; b) Morphology and word formation; c) Etymology, lexicology and semantics; d) Syntax and stylistics. This book is one of the most useful among Mongolian and foreign researchers in terms of the word formation(morphology), syntax, semantics, lexicology and stylistics.