Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
thu sach » thuat sach, thuoc sach, thu hoach
van nang » van quang, van ban, van dong
cac tac » cac toc, cac bac, cac dac
va nang » da nang, cam nang, kha nang
tu sach » su sach, te sach, tu cach
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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