Perhaps you should try some spelling variations:
vien sach » vien bach, dien sach, kien sach
viet sach » viet anh, dien sach, viet tech
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
di cua » doi cua, de cua, do 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 hanh ((di cua) OR (dai cua)) te~.
• 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 hanh ((di cua) OR (dai cua)) te.
• 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 hanh ((di cua) OR (dai cua)) te".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. hieu ((vien sach) or (viet sach)) nuoc va hanh ((di cua) OR (dai cua)) te*.