Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
thanh hai » thanh phan, thanh hoa, thanh san
thu sach » tu sach, thuat sach, thuoc sach
vien cac » vien bach, vien dai, vien da
sach ky » sac ky, sach y, sach ty
duc ban » duc van, dua ban, duc man
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
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: thu sach ky nang x hoi. hieu vien cac ((duc ban) or (duc tan)) thanh hai ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x hoi. hieu vien cac ((duc ban) OR (duc tan)) thanh hai ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x hoi. hieu vien cac ((duc ban) or (duc tan)) thanh hai ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. hieu vien cac ((duc ban) or (duc tan)) thanh hai ((cuu tre) OR (cua tre))*.