Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hang doi » hang di, hang loi, huong doi
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
mai khoi » mai khoa, tai khoa, cac khoi
mai hoi » dai hoi, lai hoi, mai doi
truc va » thuc vat, trung va
thuc va » thuc vat, thuc dan, thuc day
doi cua » dai cua, hoi cua
su sach » so sach, vu sach
y nang » ky nang, ly nang, v nang

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 y nang ((mai hoi) OR (mai khoi)). hieu van cham ((truc va) or (thuc va)) hang doi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang ((mai hoi) OR (mai khoi)). hieu van cham ((truc va) OR (thuc va)) hang doi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang ((mai hoi) OR (mai khoi)). hieu van cham ((truc va) or (thuc va)) hang doi cua viet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang ((mai hoi) OR (mai khoi)). hieu van cham ((truc va) or (thuc va)) hang doi cua viet*.