Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
thuoc ma » hoc ma, duoc ma
cau tren » cu tren, dau tren, ca tren
lang xa » lang ha, dang xay, lang van
sach ty » sach y, sach tu, sach thu
hieu va » lieu va
sach ky » sac ky, sach y, sach kem
dan van » dang van, doan van, dao van
van cau » van dau, van hau, van chat
ma dan » mat dan, mua dan, ca dan

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: doc ((sach ky) OR (sach ty)) lang xa hoi. ((hieu va) OR (hieu qua)) nam thuoc ma dan van cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((sach ky) or (sach ty)) lang xa hoi. ((hieu va) OR (hieu qua)) nam thuoc ma dan van cau tren~".
• Adding a wildcard symbol may retrieve word variants: doc ((sach ky) or (sach ty)) lang xa hoi. ((hieu va) OR (hieu qua)) nam thuoc ma dan van cau tren*.