Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
thu sach » tu sach, thuat sach, thuoc sach
hieu cac » hieu luc, hieu va, hieu van
cua viet » ca viet, hoa viet, cua vat
mai hoi » mai khoi, dai hoi, lai hoi
hanh di » hanh vi, hanh de, hang di
ma hoi » xa hoi, ma hoa, me hoi
y nang » ky nang, ly nang, v nang
loc va » hoc va, luc va
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y nang ((ma hoi) or (mai hoi)). hieu hieu cac ((duc va) or (loc va)) hanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((ma hoi) OR (mai hoi)). hieu hieu cac ((duc va) OR (loc va)) hanh di cua viet.
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((ma hoi) or (mai hoi)). hieu hieu cac ((duc va) or (loc va)) hanh di cua viet*.