411 REFERENCE · Wikibooks
Pinyin/Surface-To-Air
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
See also
Pinyin#Pinyin tone marking
dih-duih-kong
411 REFERENCE · Wikibooks
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.