Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, va tinh, le thanh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet

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 ky nang xa hoi. hieu van cau truc ((va thanh) OR (ban thanh)) ha ((cua tre) or (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. hieu van cau truc ((va thanh) OR (ban thanh)) ha ((cua tre) OR (cua vat)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. hieu van cau truc ((va thanh) OR (ban thanh)) ha ((cua tre) or (cua vat))".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. hieu van cau truc ((va thanh) OR (ban thanh)) ha ((cua tre) or (cua vat))*.