Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
va triet » va thiet, va trien, ve triet
van hang » van khang, van hoang, van thang
thuc van » thuc vat, thuc dan, thuc va
nam thuc » nam thuoc, am thuc, nam thu
hang di » hang doi, hang vi, hang dien
bo sach » co sach, hoc sach
hieu ve » hieu va, hieu van
hieu he » hiem he, hieu le, hieu hien
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

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: bo sach thu nang ma hoi. ((hieu he) OR (hieu ve)) nam thuc van hang di ((va triet) OR (su triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo sach thu nang ma hoi. ((hieu he) OR (hieu ve)) nam thuc van hang di ((va triet) or (su triet))~".
• Adding a wildcard symbol may retrieve word variants: bo sach thu nang ma hoi. ((hieu he) OR (hieu ve)) nam thuc van hang di ((va triet) or (su triet))*.