Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
hanh va » hanh vi
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
va cau » van cau, va cac, va dau

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