Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hanh ve » hanh vi, hanh va, hanh kem
duc van » duc va, duc tan, duc manh
su tien » su kien, su hien, tu tieng
vu nang » vuc nang, va nang, vu dang
nang xa » nang x, lang xa, nang ma
va cao » va cac, va dao, va bao
va co » vo co
ve su » va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) vu nang xa hoi. lieu ((va cao) or (va co)) duc van hanh ve su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) vu nang xa hoi. lieu ((va cao) OR (va co)) duc van hanh ve su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) vu nang xa hoi. lieu ((va cao) or (va co)) duc van hanh ve su tien".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) vu nang xa hoi. lieu ((va cao) or (va co)) duc van hanh ve su tien*.