Perhaps you should try some spelling variations:
viet sach » viet anh, dien sach, viet tech
vien sach » vien bach, dien sach, kien sach
hanh de » hanh ve, hanh kem
hanh di » hanh vi, hang di, danh di
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cua te » cua tu

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) OR (hanh de)) 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) OR (hanh de)) 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) OR (hanh de)) 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) OR (hanh de)) cua te*.