Perhaps you should try some spelling variations:
thien van » thi van
nam thuc » nam thuoc, am thuc, nam thu
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
sach lo » sach dao, sach doi, sach hoi
nang ma » tang ma, sang ma, nang cao
lo nang » ho nang, ly nang, loai nang
hieu va » lieu va, hieu qua
ma hoi » mai hoi, xa hoi, ma hoa
di cua » doi cua, de cua, do 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: su sach lo nang ma hoi. ((thien van) OR (hieu va)) nam thuc va danh ((di cua) OR (dai cua)) viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach lo nang ma hoi. ((thien van) or (hieu va)) nam thuc va danh ((di cua) OR (dai cua)) viet~".
• Adding a wildcard symbol may retrieve word variants: su sach lo nang ma hoi. ((thien van) or (hieu va)) nam thuc va danh ((di cua) OR (dai cua)) viet*.