Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
van hanh » ban hanh, van anh, van ban
te sach » toc sach
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
ty nang » ky nang, ty xang, ty hang
cac bo » bac bo
cac co » cac cong
nang o » nang co, nang ho, nang ro
vi cua » vai cua, di cua
o hai » co hai, so hai, o lai

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 ty nang o hai. lieu va ((cac bo) or (cac co)) ((van hanh) OR (van thanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang o hai. lieu va ((cac bo) OR (cac co)) ((van hanh) OR (van thanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang o hai. lieu va ((cac bo) or (cac co)) ((van hanh) OR (van thanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang o hai. lieu va ((cac bo) or (cac co)) ((van hanh) OR (van thanh)) vi cua tre*.