Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
nang noi » nang doc
nang doi » nang doc, hang doi, nang dong
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
ky dang » ky nang, ky danh
cac tac » cac toc, cac bac, cac dac
tac xa » tuc xa, tac da
ha hoi » hoa hoi, ha noi, va hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky dang ((ha hoi) OR (xa hoi)). hieu va cac tac xa ((nang doi) or (nang noi)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang ((ha hoi) OR (xa hoi)). hieu va cac tac xa ((nang doi) OR (nang noi)) va triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang ((ha hoi) OR (xa hoi)). hieu va cac tac xa ((nang doi) or (nang noi)) va triet*".