User:Engirst
- Basic Rules of Hanyu Pinyin Orthography (Summary)
- Wordproject Pinyin Bible
- Pīnyīn Rìjì Duǎnwén (Pinyin Diary)
- Pinyin - Wikibooks
- Pinyin - Wikipedia
- Wenlin Pinyin dictionary
- Pleco dictionary for iPhone
- This should be a good solution. There is no duplication of entries of the dictionary of this "good solution". Please see the search results of "蘋果", "苹果", "ping2guo3" and "pingguo", there is no duplication indeed. (Please see here for reference.)