Perhaps you should try some spelling variations:
hieu vien » hieu viec, thieu nien, hieu tieng
hieu hien » bieu hien, dieu hien, chieu chien
tinh vi » trinh vi, tinh voi, tinh va
va tinh » may tinh
sach ky » sac ky, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
nang ho » nang hoc, nang co, tang ho
ho hoi » hoc hoi, hoa hoi, hoi hoi
dai va » mai va
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) OR (sach y)) nang ho hoi. ((hieu vien) or (hieu hien)) can dai va tinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) nang ho hoi. ((hieu vien) OR (hieu hien)) can dai va tinh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach y)) nang ho hoi. ((hieu vien) or (hieu hien)) can dai va tinh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach y)) nang ho hoi. ((hieu vien) or (hieu hien)) can dai va tinh vi cua tre*.