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

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