Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh doi » thanh doi, hanh noi, hang doi
thuc dan » thuc hanh, hoc dan, thuc vat
van tham » van thanh, van tuan, van chat
cua viet » ca viet, hoa viet, cua vat
nang ho » nang hoc, nang co, nang cao
thuc va » thuc vat, thuc day
tang ho » tang cho, tung ho, tang ha
doi cua » dai cua, hoi cua
su cac » tu cac, su cao, su can

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

• Performing a fuzzy search may retrieve terms with similar spellings: su cac ky ((nang ho) OR (tang ho)) hoi. hieu van tham ((thuc va) or (thuc dan)) hanh doi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su cac ky ((nang ho) OR (tang ho)) hoi. hieu van tham ((thuc va) OR (thuc dan)) hanh doi cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su cac ky ((nang ho) OR (tang ho)) hoi. hieu van tham ((thuc va) or (thuc dan)) hanh doi cua viet*".