Perhaps you should try some spelling variations:
thien van » thi van
thu sach » tu sach, thuat sach, thuoc sach
lam duc » lam duoc, pham duc, nam duoc
luu tre » luu tru, cuu tre, luy tre
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi
va dau » va dao
dau ta » dau tai, dau tam, dau tu
ta luu » tam luu
o hoi » o hoc, o hai, o hoa

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 y nang ((o hoi) OR (co hoi)). ((lieu va) or (thien van)) lam duc va dau ta luu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((o hoi) OR (co hoi)). ((lieu va) OR (thien van)) lam duc va dau ta luu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((o hoi) OR (co hoi)). ((lieu va) or (thien van)) lam duc va dau ta luu tre*".