Perhaps you should try some spelling variations:
manh hanh » xanh hanh, danh thanh, minh thanh
thu sach » thuat sach, thuoc sach, thu hoach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cac suc » cao suc, cac cuoc, cac quoc
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
tu lang » cu lang, tu lanh, xu lang
tu sach » su sach, te sach, tu cach
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: ((thu sach) or (tu sach)) tu lang xa hoi. hieu ve ((cac suc) OR (cac nuoc)) manh hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) tu lang xa hoi. hieu ve ((cac suc) OR (cac nuoc)) manh hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (tu sach)) tu lang xa hoi. hieu ve ((cac suc) OR (cac nuoc)) manh hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (tu sach)) tu lang xa hoi. hieu ve ((cac suc) OR (cac nuoc)) manh hanh vi cua tre*.