Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
nhan thai » nhanh thai, nhan tai, nhan tham
thai cua » than cua, tai cuc, tri cua
thu sach » thuat sach, thuoc sach, thu hoach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
vien cac » vien bach, vien dai, vien da
tu sach » te sach, tu cach, vu sach
va nhan » van nhan, ca nhan, va phan
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet

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 (su sach))) or (thu sach)) ky tang xa hoi. hieu vien cac nuoc va nhan thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (su sach))) OR (thu sach)) ky tang xa hoi. hieu vien cac nuoc va nhan thai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((tu sach) OR (su sach))) or (thu sach)) ky tang xa hoi. hieu vien cac nuoc va nhan thai cua tre*".