Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
doanh van » doan van, doanh va, doanh ban
va doanh » van doanh, vay doanh, va danh
sach ky » sac ky, sach y, sach kem
van cua » vang cua, ban cua, dan cua
vien da » vien dai, hien dai
nang ma » tang ma, sang ma, nang cao
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
da bo » da bao, do bo, da 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: tu ((sach ky) or (sach ty)) nang ma hoi. hieu vien da bo va doanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) nang ma hoi. hieu vien da bo va doanh van cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach ty)) nang ma hoi. hieu vien da bo va doanh van cua tre*.