Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
cua viet » ca viet, hoa viet, cua vat
hanh vai » hanh vi, hanh va, hanh tai
tru nang » tra nang, tri nang, truc nano
mai hoi » mai khoi, dai hoi, lai hoi
tu nang » tu nong, tu nano, tu lang
vai cua » dai cua, hai cua, lai cua
tu sach » thu sach, su sach, te sach
xuc va » tuc va, luc va, xac va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((tu nang) OR (tru nang)) mai hoi. hieu vien bach ((xuc va) or (duc va)) hanh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((tu nang) OR (tru nang)) mai hoi. hieu vien bach ((xuc va) OR (duc va)) hanh vai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((tu nang) OR (tru nang)) mai hoi. hieu vien bach ((xuc va) or (duc va)) hanh vai cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((tu nang) OR (tru nang)) mai hoi. hieu vien bach ((xuc va) or (duc va)) hanh vai cua viet*.