Perhaps you should try some spelling variations:
sieu viet » dien viet, bien viet, viet viet
dat ngoc » dat nuoc, dau ngoc, dang ngoc
va trinh » van trinh, lap trinh, qua trinh
viet cua » viec cua, viet ca, viet qua
va tinh » may tinh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
su viet » so viet
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet

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 nang xa hoi. ((sieu viet) OR (su viet)) dat ngoc ((va trinh) or (va tinh)) viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. ((sieu viet) OR (su viet)) dat ngoc ((va trinh) OR (va tinh)) viet cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. ((sieu viet) OR (su viet)) dat ngoc ((va trinh) or (va tinh)) viet cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. ((sieu viet) OR (su viet)) dat ngoc ((va trinh) or (va tinh)) viet cua tre*.