Perhaps you should try some spelling variations:
tai nhanh » tai thanh, thai thanh, tai chinh
nhanh cau » nhanh cay, thanh chau, nhanh ha
cau tren » cu tren, dau tren, ca tren
sach tai » sach bai, sach tham, sach dao
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
hanh va » hang va, hanh vi
vu sach » vu bach, su sach, vu khach
cam duc » cam xuc, pham duc, nam duoc
cao duc » dao duc, cao suc, giao duc

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach tai nhanh cau hoi. hieu qua ((cam duc) or (cao duc)) van hanh va ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach tai nhanh cau hoi. hieu qua ((cam duc) OR (cao duc)) van hanh va ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: vu sach tai nhanh cau hoi. hieu qua ((cam duc) or (cao duc)) van hanh va ((cua tre) or (cau tren))*.