The most recent rerelease from Sino-Platonic Papers is The Family of Chinese Character-Type Scripts, by Zhou Youguang, one of the main people behind the creation of Hanyu Pinyin. So it’s no surprise that his name has come up before in Pinyin News.
This article, from September 1991, categorizes and briefly discusses more than a dozen scripts derived from Chinese characters, most of which were used inside China by non-Han people.
The link above is to an HTML version. The original format of the article is preserved in the PDF file (650 KB).