Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
thu sach » thuat sach, thuoc sach, thu hoach
cam thuc » am thuc, nam thuc, cam thu
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu sach » su sach, te sach, tu cach
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
ma hoi » mai hoi, xa hoi, ma hoa
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: ((tu sach) or (thu sach)) ky tang ma hoi. ((hieu van) or (thien van)) cam thuc va hanh di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky tang ma hoi. ((hieu van) OR (thien van)) cam thuc va hanh di cua vat.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky tang ma hoi. ((hieu van) or (thien van)) cam thuc va hanh di cua vat*.