I read a Japanese essay book Maketara Akan!, written by Yuriko Ishikawa and Mari Ishikawa.
Mari was a woman who once suffered from selective mutism more than 10 years. Yuriko was her mother. The book is about their fight against selective mutism and impulse to suicide.
There is another essay book about selective mutism in Japan. Kimino Tonarini, written by Kayo Sakura who also suffered from selective mutism.
I suppose that it is Japanese culture to publish essays about selective mutism. We can find many Japanese essays written by SM sufferer, ex sufferer and their mothers in the blogsphere. Among them, Selective Mutism - My Memories is the first English blog that is translated from Japanese. :)
Index of SM in Japan