Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
hieu van » thien van, lieu va, hieu ve
ban hanh » ban hang
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
xuc ban » duc ban, cuc ban, quoc ban
cua tre » cua te, cuu tre, cua triet
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 (doc sach)) ky lang xa hoi. ((hieu van) or (hieu va)) cam xuc ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky lang xa hoi. ((hieu van) OR (hieu va)) cam xuc ban hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ky lang xa hoi. ((hieu van) or (hieu va)) cam xuc ban hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky lang xa hoi. ((hieu van) or (hieu va)) cam xuc ban hanh vi cua tre*.