Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cham tuc » nham thuc, pham thuc, tham thuc
vu sach » vu bach, su sach, vu khach
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
tuc va » thuc va, truc va, tuc xa
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sach) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cham tuc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cham tuc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cham tuc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cham tuc va hanh vi cua tre*.