Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
va hanh » van hanh, va thanh, va danh
cao tuc » dao tuc, cao duc, cao suc
hieu va » hieu qua
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano
cua tre » cua te, cuu tre, cua triet
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: ((toc sach) or (hoc sach)) tu nang xa hoi. ((hieu va) OR (lieu va)) cao tuc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) tu nang xa hoi. ((hieu va) OR (lieu va)) cao tuc va hanh vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) tu nang xa hoi. ((hieu va) OR (lieu va)) cao tuc va hanh vi cua tre*".