Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
doc sac » doc sach, dac sac, hoc sach
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va, hieu qua
cau luc » cau phuc
sac ky » cac ky, sai ky
ve cua » de cua, te cua, ve cum
le cua » ly cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sac ky nang cao hoi. hieu va ((cau luc) or (cau truc)) van hanh ((ve cua) OR (le cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sac ky nang cao hoi. hieu va ((cau luc) OR (cau truc)) van hanh ((ve cua) OR (le cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sac ky nang cao hoi. hieu va ((cau luc) or (cau truc)) van hanh ((ve cua) OR (le cua)) tre".
• Adding a wildcard symbol may retrieve word variants: doc sac ky nang cao hoi. hieu va ((cau luc) or (cau truc)) van hanh ((ve cua) OR (le cua)) tre*.