Perhaps you should try some spelling variations:
"sung and soon letters" » "dung and soon letters", "cung and soon letters", "ung and soon letters", "sung and soan letters", "sung and son letters"
"sung and yoon letters" » "dung and yoon letters", "cung and yoon letters", "ung and yoon letters"
"song and moon letters" » "cong and moon letters", "dong and moon letters", "song and mon letters", "song and muon letters"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("sung and soon letters") or ("sung and yoon letters"))) or ("song and moon letters"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("sung and soon letters") OR ("sung and yoon letters"))) OR ("song and moon letters")).
• Removing quotes may allow a broader search: (((( sung and soon letters ) or ( sung and yoon letters ))) or ( song and moon letters )).
• Adding a wildcard symbol may retrieve word variants: (((("sung and soon letters") or ("sung and yoon letters"))) or ("song and moon letters"))*.