Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
danh ki » danh di, danh kien, danh gia
su tien » su kien, su hien, tu tieng
ve cac » va cac, vien cac
dac va » day va, dat va, dai va
ki su » ky su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang xa hoi. hieu ve cac ((dac va) OR (duc va)) danh ki su tien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. hieu ve cac ((dac va) OR (duc va)) danh ki su tien".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu ve cac ((dac va) OR (duc va)) danh ki su tien*.