Perhaps you should try some spelling variations:
dat thanh » dao thanh, dat khanh, dang thanh
vat thanh » gat thanh, tat thanh, viet thanh
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
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 thuc ((vat thanh) OR (dat thanh)) va ((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 thuc ((vat thanh) OR (dat thanh)) va ((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 thuc ((vat thanh) OR (dat thanh)) va ((cua tre) or (cua vat))".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. hieu van cau thuc ((vat thanh) OR (dat thanh)) va ((cua tre) or (cua vat))*.