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
hieu va » lieu va, hieu qua
va nang » van nang, da nang, cam nang
vu nang » vuc nang, vu dang, v nang
su sach » so sach, vu sach

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 ((vu nang) OR (va nang)) xa 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 ((vu nang) OR (va nang)) xa 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 ((vu nang) OR (va nang)) xa hoi. hieu va cac thuc van ((hang don) or (hang doi)) su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((vu nang) OR (va nang)) xa hoi. hieu va cac thuc van ((hang don) or (hang doi)) su triet*.