Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
thu nang » thi nang, thu hang, thu bang
ve triet » va trien, su triet
nam duc » nam duoc, pham duc, nam thuc
hanh de » hanh ve, hanh kem
hang di » hang doi, hang vi, hang dien
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach thu nang ((o hoi) OR (o hai)). hieu van nam duc va ((hanh de) or (hang di)) ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach thu nang ((o hoi) OR (o hai)). hieu van nam duc va ((hanh de) OR (hang di)) ve triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach thu nang ((o hoi) OR (o hai)). hieu van nam duc va ((hanh de) or (hang di)) ve triet*".