Perhaps you should try some spelling variations:
thien van » thi van
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, lieu va, hieu ve
sach ly » sach y, sach lo, sach ty
lam cuu » lam chu, lam cua, cham cuu
ly nang » ky nang, ly hang, ly vang
hanh di » hanh vi, hanh de, hang di
di cua » dai cua, doi cua, de cua
cua te » cua tu
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: thu sach ly nang ((x hoi) or (o hoi)). ((hieu van) OR (thien van)) lam cuu van hanh di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ly nang ((x hoi) OR (o hoi)). ((hieu van) OR (thien van)) lam cuu van hanh di cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ly nang ((x hoi) or (o hoi)). ((hieu van) OR (thien van)) lam cuu van hanh di cua te".
• Adding a wildcard symbol may retrieve word variants: thu sach ly nang ((x hoi) or (o hoi)). ((hieu van) OR (thien van)) lam cuu van hanh di cua te*.