Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
toc sach » hoc sach, doc sach, thuoc sach
tinh de » tinh da, sinh de, tinh he
va tinh » may tinh
cac duc » cac du, cao duc, cac dac
hieu va » lieu va
xang o » lang o, tang o, dang o
y xang » ty xang
de cua » le cua, te cua, dieu cua
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) y xang o hoi. ((hieu va) OR (hieu qua)) cac duc va tinh de cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y xang o hoi. ((hieu va) OR (hieu qua)) cac duc va tinh de cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) y xang o hoi. ((hieu va) OR (hieu qua)) cac duc va tinh de cua triet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) y xang o hoi. ((hieu va) OR (hieu qua)) cac duc va tinh de cua triet*.