Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
cao nang » cao dang, cam nang, cao tang
hanh doi » thanh doi, hanh noi, hang doi
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
nam thuc » nam thuoc, am thuc, nam thu
sach cao » sach dao, sach cap, mach cao
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
doi cua » dai cua, hoi cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach cao nang ((xa hoi) OR (mai hoi)). ((hieu van) OR (hieu va)) nam thuc van hanh doi cua vat~.
• Adding a wildcard symbol may retrieve word variants: tu sach cao nang ((xa hoi) or (mai hoi)). ((hieu van) or (hieu va)) nam thuc van hanh doi cua vat*.