Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hanh tai » thanh tai, hang tai, han tai
ly quang » le quang, vu quang
co sach » bo sach, cuon sach, hoc sach
va hanh » van hanh, va thanh, va danh
cuc tre » duc tre, cua tre, cuu tre
tuc va » thuc va, truc va, tuc xa
ve cac » va cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: co sach ((ly hang) or (ly quang)) xa hoi. hieu ((ve cac) OR (vien cac)) tuc va hanh tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co sach ((ly hang) OR (ly quang)) xa hoi. hieu ((ve cac) OR (vien cac)) tuc va hanh tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "co sach ((ly hang) or (ly quang)) xa hoi. hieu ((ve cac) OR (vien cac)) tuc va hanh tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: co sach ((ly hang) or (ly quang)) xa hoi. hieu ((ve cac) OR (vien cac)) tuc va hanh tai cuc tre*.