Perhaps you should try some spelling variations:
dieu hien » dieu khien, dieu kien, bieu hien
hieu hien » bieu hien, chieu chien, dieu khien
dinh vai » dinh van, dinh vi, dinh va
vai cuu » vai cua
va dinh » van dinh, va kinh, va tinh
cuu tre » cua tre, cau tren, cau treo
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cac bo » bac bo, cac co
bo va » bao va, do va, so 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 ky) or (sach y)) nang xa hoi. ((hieu hien) OR (dieu hien)) cac bo va dinh vai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ky) OR (sach y)) nang xa hoi. ((hieu hien) OR (dieu hien)) cac bo va dinh vai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ky) or (sach y)) nang xa hoi. ((hieu hien) OR (dieu hien)) cac bo va dinh vai cuu tre".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) or (sach y)) nang xa hoi. ((hieu hien) OR (dieu hien)) cac bo va dinh vai cuu tre*.