Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
lang van » dang van, tang van, hoang van
va hanh » van hanh, va thanh, va danh
cau duc » cao duc, cau luc, chu duc
hieu va » lieu va, hieu qua
hieu ve » hieu van
lang xa » lang ha, dang xay
cu tren » tu tren, dua tren
vi cu » vi su, vi xu, vi du

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 y ((lang xa) or (lang van)) hoi. ((hieu ve) or (hieu va)) cau duc va hanh vi cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((lang xa) OR (lang van)) hoi. ((hieu ve) OR (hieu va)) cau duc va hanh vi cu tren.
• Adding a wildcard symbol may retrieve word variants: thu sach y ((lang xa) or (lang van)) hoi. ((hieu ve) or (hieu va)) cau duc va hanh vi cu tren*.