Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
va thanh » gia thanh, ban thanh, va tinh
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va danh, ban hanh
su sach » so sach, vu sach
hieu te » hieu ve, hien te, hieu he
ban co » ban do
va cau » van cau, va cac, va dau
san co » sang cho
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang x hoi. hieu te ((ban co) OR (san co)) ((va hanh) or (va thanh)) va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang x hoi. hieu te ((ban co) OR (san co)) ((va hanh) OR (va thanh)) va cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang x hoi. hieu te ((ban co) OR (san co)) ((va hanh) or (va thanh)) va cau tren".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. hieu te ((ban co) OR (san co)) ((va hanh) or (va thanh)) va cau tren*.