Perhaps you should try some spelling variations:
viet sach » viet anh, dien sach, viet tech
vien sach » vien bach, dien sach, kien sach
va dinh » van dinh, va kinh, va tinh
va danh » va dan, va hanh, dia danh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de 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 nang xa hoi. hieu ((vien sach) or (viet sach)) nuoc ((va danh) OR (va dinh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. hieu ((vien sach) OR (viet sach)) nuoc ((va danh) OR (va dinh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. hieu ((vien sach) or (viet sach)) nuoc ((va danh) OR (va dinh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. hieu ((vien sach) or (viet sach)) nuoc ((va danh) OR (va dinh)) di cua tre*.