Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
hang vai » hang tai, hang hai, hang vi
thu sach » thuat sach, thuoc sach, thu hoach
cac duc » cac du, cao duc, cac dac
duc ban » duc tan, duc van, dua ban
tu sach » su sach, te sach, tu cach
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho

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) OR (thu sach)) y nang x hoi. hieu vien cac duc ban ((hang vai) or (hang va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) y nang x hoi. hieu vien cac duc ban ((hang vai) OR (hang va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) y nang x hoi. hieu vien cac duc ban ((hang vai) or (hang va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) y nang x hoi. hieu vien cac duc ban ((hang vai) or (hang va)) cua tre*.