Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
hanh dai » hanh tai, hanh dao, vanh dai
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
cua viet » ca viet, hoa viet, cua vat
mai hoi » mai khoi, dai hoi, lai hoi
sach lo » sach dao, sach doi, sach hoi
lo nang » ho nang, ly nang, loai nang
tu sach » thu sach, su sach, te sach
ma hoi » xa hoi, ma hoa, me hoi

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 lo nang ((ma hoi) or (mai hoi)). ((hieu quan) or (hieu qua)) nam thuc dan hanh dai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach lo nang ((ma hoi) OR (mai hoi)). ((hieu quan) OR (hieu qua)) nam thuc dan hanh dai cua viet.
• Adding a wildcard symbol may retrieve word variants: tu sach lo nang ((ma hoi) or (mai hoi)). ((hieu quan) or (hieu qua)) nam thuc dan hanh dai cua viet*.