After several previous attempts to write Chinese using the letters of the roman alphabet, pinyin, a 58-symbol writing system was finally adopted in 1958. Some strange and unnatural sounds for the x's, q's, and zh's reflect the graphic choices of Russian linguists. Its main aims are to facilitate the spread of putonghua, and the learning of Chinese characters. In the 1970s a new map of China was published using the alphabet, and a list of standard spellings for Chinese placenames was compiled.