Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
thuc day » thuc dan, thuc vat
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
hang doi » hang di, hang loi, huong doi
doi cua » dai cua, hoi cua
su sach » so sach, vu sach
thuc va » thuc vat, thuc dan
mai hoi » mai khoi, dai hoi, lai hoi
truc va » thuc vat, trung va
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. hieu van cham ((truc va) or (((thuc va) OR (thuc day)))) hang doi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang mai hoi. hieu van cham ((truc va) OR (((thuc va) OR (thuc day)))) hang doi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang mai hoi. hieu van cham ((truc va) or (((thuc va) OR (thuc day)))) hang doi cua viet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang mai hoi. hieu van cham ((truc va) or (((thuc va) OR (thuc day)))) hang doi cua viet*.