Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
dang thai » dang thi, dang hai, dang khai
hieu van » thien van, lieu va, hieu ve
thai cua » than cua, tai cuc, tri cua
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
lang van » dang van, tang van, hoang van
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
va dang » van dang, va nang, va lang
lang xa » lang ha, dang xay
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach ky ((lang xa) OR (lang van)) hoi. ((hieu van) or (hieu va)) cac nuoc va dang thai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky ((lang xa) OR (lang van)) hoi. ((hieu van) OR (hieu va)) cac nuoc va dang thai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky ((lang xa) OR (lang van)) hoi. ((hieu van) or (hieu va)) cac nuoc va dang thai cua te".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky ((lang xa) OR (lang van)) hoi. ((hieu van) or (hieu va)) cac nuoc va dang thai cua te*.