Perhaps you should try some spelling variations:
thanh day » thanh dat, thanh tay, thanh dam
hieu vien » hieu hien, hieu viec, thieu nien
dai khoa » da khoa, dac khoa, dai hoa
tai khoa » da khoa, noi khoa
va thanh » gia thanh, ban thanh, va tinh
cau luc » cau truc, cau phuc
day cuu » day cua, day chu, day cuon
so sach » so sanh, bo sach, co sach
cac luc » coc luc, cac nuoc, cac cuoc
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo

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