Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
thanh day » thanh dat, thanh tay, thanh dam
dai khoa » da khoa, tai khoa, dac khoa
vien cac » vien bach, vien dai, vien da
so sach » so sanh, bo sach, co sach
ty nang » ty xang, ty hang, ly nang
day cuu » day cua, day chu, day cuon
cuu tre » cua tre, cau tren, cau treo
luc va » tuc va, loc va

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 ((ty nang) OR (ky nang)) dai khoa. hieu vien cac ((luc va) or (duc va)) thanh day cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ty nang) OR (ky nang)) dai khoa. hieu vien cac ((luc va) OR (duc va)) thanh day cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ty nang) OR (ky nang)) dai khoa. hieu vien cac ((luc va) or (duc va)) thanh day cuu tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ty nang) OR (ky nang)) dai khoa. hieu vien cac ((luc va) or (duc va)) thanh day cuu tre*.