Perhaps you should try some spelling variations:
sach nuoc » sach duoc, cac nuoc, bach tuoc
hieu viec » nhieu viec, sieu viet, hieu hien
huong doi » huong dan, trong doi
dung doi » dung tai, dung co, dung mo
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
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: su sach ky nang xa hoi. ((hieu viec) or (hieu ve)) sach nuoc va ((dung doi) OR (huong doi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. ((hieu viec) OR (hieu ve)) sach nuoc va ((dung doi) OR (huong doi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. ((hieu viec) or (hieu ve)) sach nuoc va ((dung doi) OR (huong doi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. ((hieu viec) or (hieu ve)) sach nuoc va ((dung doi) OR (huong doi)) cua tre*.