Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
va thanh » gia thanh, ban thanh, va tinh
va hanh » van hanh, va danh, ban hanh
sach ky » sac ky, sach y, sach ty
vu sach » vu bach, su sach, vu khach
hieu te » hieu ve, hien te, hieu he
te ban » te bao
vi cau » va cau, ve cau, di cau
ban co » ban do, san co
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

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