#study textbooks

You may download them using the Library of Genesis (the pirate way) or google the names and buy/rent them (the honest way).

The Second Circle by Patsy Rodenburg; 

Actor Training The Laban Way: An Integrated Approach to Voice, Speech, and Movement by Barbara Adrian;

Pronouncing Dictionary of American English by John S. Kenyon and Thomas A. Knott;    

Freeing the Natural Voice by Kristen Linklater;

Voice: Onstage and Off by Robert Barton and Rocco Dal Vera;

Public Speaking by Michael Osborn & Susanne Osborn, 8th Edition.

For those with Russian as mother tongue: