Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh di » thanh doi, thanh de, thanh do
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
su sach » so sach, vu sach
sach ly » sach y, sach lo, sach ty
cam tuc » cam xuc, cam tu, dam thuc
su viet » so viet
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
di su » doi su, ki su, da su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ly ((nang xa) or (dang xay)) hoi. hieu va ((cam tuc) OR (nam thuc)) ban thanh di su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly ((nang xa) OR (dang xay)) hoi. hieu va ((cam tuc) OR (nam thuc)) ban thanh di su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly ((nang xa) or (dang xay)) hoi. hieu va ((cam tuc) OR (nam thuc)) ban thanh di su viet".
• Adding a wildcard symbol may retrieve word variants: su sach ly ((nang xa) or (dang xay)) hoi. hieu va ((cam tuc) OR (nam thuc)) ban thanh di su viet*.