Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
phuc may » hoc may, chua may, phan may
truc may » tren may, truc va
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
tinh vi » trinh vi, tinh voi, tinh va
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang ((co hoi) or (xa hoi)). hieu van nam ((phuc may) OR (truc may)) tinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((co hoi) OR (xa hoi)). hieu van nam ((phuc may) OR (truc may)) tinh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((co hoi) or (xa hoi)). hieu van nam ((phuc may) OR (truc may)) tinh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((co hoi) or (xa hoi)). hieu van nam ((phuc may) OR (truc may)) tinh vi cua tre*.