Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
van hanh » ban hanh, van anh, van ban
lang van » dang van, tang van, hoang van
su sach » so sach, vu sach
dau tuc » dau tu, dao tuc, cau truc
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang ma) or (lang van)) hoi. lieu va dau tuc ((van hanh) OR (van thanh)) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang ma) OR (lang van)) hoi. lieu va dau tuc ((van hanh) OR (van thanh)) doi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang ma) or (lang van)) hoi. lieu va dau tuc ((van hanh) OR (van thanh)) doi cua tre*".