This book was published in 2002 at the occasion of the International STI symposium in Soesterberg. It gives a good overview of the general background, algorithms, history and some applications of the STI.
White paper on the use of STIPA testing tools
This is the dissertation of Sander van Wijngaarden. It contains a quantitative investigation into the effects of non-native speech perception (and production) on intelligibility. It also outlines how to interpret STI measurements in case of accented speech.
Our general conditions are found here (English, Dutch). KvK / Chamber of Commerce The Hague nr 50227092.