Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
dinh dai » sinh dai, dinh dao, dinh tai
dinh dat » dinh ket, dinh van, dinh lam
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
xu va » xu van, tu va, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang xa hoi. ((hieu van) or (hieu va)) chao xu va ((dinh dai) OR (dinh dat)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang xa hoi. ((hieu van) OR (hieu va)) chao xu va ((dinh dai) OR (dinh dat)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang xa hoi. ((hieu van) or (hieu va)) chao xu va ((dinh dai) OR (dinh dat)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang xa hoi. ((hieu van) or (hieu va)) chao xu va ((dinh dai) OR (dinh dat)) cuu tre*.