Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
sach thi » sach thu, sach tai, sach thieu
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
hieu ve » hieu va
hang ca » hang va, nang cao, hang tai
hang xa » hoang xa, hang va, lang xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thi ((hang xa) or (hang ca)) hoi. ((hieu ve) OR (hieu van)) tham thuc va hanh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thi ((hang xa) OR (hang ca)) hoi. ((hieu ve) OR (hieu van)) tham thuc va hanh vai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thi ((hang xa) or (hang ca)) hoi. ((hieu ve) OR (hieu van)) tham thuc va hanh vai cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach thi ((hang xa) or (hang ca)) hoi. ((hieu ve) OR (hieu van)) tham thuc va hanh vai cua viet*.