I asked this question a week ago, but there were no responses. Basically I wonder are there any books about that part of history of India.
The most trustworthy will be in french.
La Bactriane sous les Kushans: problèmes d'histoire et de culture by B. Ja. Staviskij; P. Bernard; M. Burda; F. Grenet; P. Leriche (1984)
In english old but it is still available on the net.
The Kushan, or Indo-Scythian, Period of Indian History, B.C. 165 to A.D. 320.Journal of the Royal Asiatic Society. January, 1903.Vincent A. Smith