Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
thu nong » thu cong, phu nong, thi nong
hanh lai » hanh lam, hanh tai, thanh lap
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
tu nong » tu dong, tu cong, tu tong
va cam » va cham, va cac, va cao
lai va » loai va, mai va, dai va
ve cai » va cai, ve cac, ve tai

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 ((thu nong) OR (tu nong)) xa hoi. hieu ((ve cai) or (va cam)) duc va hanh lai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((thu nong) OR (tu nong)) xa hoi. hieu ((ve cai) OR (va cam)) duc va hanh lai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((thu nong) OR (tu nong)) xa hoi. hieu ((ve cai) or (va cam)) duc va hanh lai va triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((thu nong) OR (tu nong)) xa hoi. hieu ((ve cai) or (va cam)) duc va hanh lai va triet*.