Perhaps you should try some spelling variations:
canh thanh » danh thanh, anh thanh, nhanh thanh
phan thong » phan thuong, phan hong, phan tong
thong song » thong cong, thong dong, thong hong
hieu lang » chieu sang, hieu quang, nhieu tang
van thanh » ban thanh, van tuan
hoc hieu » hoc thieu, hoc hien, doc hieu
van toan » van tuan, van tan, manh toan

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu lang - ((canh thanh) OR (canh tranh)) phan thong song ((van toan) or (van thanh)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - ((canh thanh) OR (canh tranh)) phan thong song ((van toan) OR (van thanh)) tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - ((canh thanh) OR (canh tranh)) phan thong song ((van toan) or (van thanh)) tap".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - ((canh thanh) OR (canh tranh)) phan thong song ((van toan) or (van thanh)) tap*.