Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hieu van » thien van, hieu ve
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
dang tri » dang thi, dung tri, dong tri
sach ky » sac ky, sach y, sach ty
ky sang » ky nang, ky dang, ky tang
sang xa » song xa, lang xa, sang ma
hieu va » hieu qua
va dang » van dang, va nang, va lang
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 sang xa hoi. ((((hieu van) OR (hieu va))) or (lieu va)) cac nuoc va dang tri cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky sang xa hoi. ((((hieu van) OR (hieu va))) OR (lieu va)) cac nuoc va dang tri cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky sang xa hoi. ((((hieu van) OR (hieu va))) or (lieu va)) cac nuoc va dang tri cua te".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky sang xa hoi. ((((hieu van) OR (hieu va))) or (lieu va)) cac nuoc va dang tri cua te*.