Perhaps you should try some spelling variations:
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
sach ky » sac ky, sach y, sach kem
cau duc » cao duc, cau luc, chu duc
van cau » van dau, van hau, van chat
thi van » thi lan, thi hanh, thi nang
sach ty » sach y, sach tu, sach thu
chu tre » cho tre, chu tri, cuu tre
va chu » va che, va cau, va chi
x hoi » xa hoi, o hoi, x ho

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 ky) or (sach ty)) nang x hoi. thi van cau duc ((van hanh) OR (ban hanh)) va chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach ty)) nang x hoi. thi van cau duc ((van hanh) OR (ban hanh)) va chu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sach ty)) nang x hoi. thi van cau duc ((van hanh) OR (ban hanh)) va chu tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sach ty)) nang x hoi. thi van cau duc ((van hanh) OR (ban hanh)) va chu tre*.