Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh tai, hanh van
so sach » so sanh, bo sach, co sach
hanh va » hang va, hanh vi
cac duc » cac du, cao duc, cac dac
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
cai hoi » cau hoi, dai hoi, cai hoa
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang

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

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