Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hang doi » hang di, hang loi, huong doi
hang don » hang ton, dang don, hang do
thuc van » thuc vat, thuc dan, thuc va
cac thuc » cach thuc, cac thu, can thuc
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
hieu va » lieu va, hieu qua
sach v » sach va, sach y, sach 2

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 v ((nang xa) OR (nang ma)) hoi. hieu va cac thuc van ((hang don) or (hang doi)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((nang xa) OR (nang ma)) hoi. hieu va cac thuc van ((hang don) OR (hang doi)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v ((nang xa) OR (nang ma)) hoi. hieu va cac thuc van ((hang don) or (hang doi)) su triet".
• Adding a wildcard symbol may retrieve word variants: su sach v ((nang xa) OR (nang ma)) hoi. hieu va cac thuc van ((hang don) or (hang doi)) su triet*.