Nikolay Rimsky-Korsakov 
Principles of Orchestration, with Musical Examples Drawn from His Own Works [EPUB ebook] 

Principles of Orchestration, with Musical Examples Drawn from His Own Works is a book by a famous Russian composer Nikolai Rimsky-Korsakov, member of the group of composers known as The Five. The book presents a notable attempt to show all of the nuances of orchestration. The author describes everything one needs to know about arranging parts for a string or full orchestra. The book is concise, articulate and excels at being both a book of reference and a book of general knowledge.