Perhaps you should try some spelling variations:
chet duoc » che duoc, cho duoc, che quoc
cua triet » cua viet, su triet, va triet
dan vat » dang vat, van vat, dan va
dan vai » dan va, dan tai, den vai
duoc va » nuoc va, duc va, duoc ma
hieu va » lieu va, hieu qua
te sach » toc sach
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
va chet » va chiet, va che, va chat
sach v » sach va, sach y, sach 2

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 v ((nang ma) or (tang ma)) hoi. hieu va chet duoc va ((dan vai) OR (dan vat)) cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach v ((nang ma) OR (tang ma)) hoi. hieu va chet duoc va ((dan vai) OR (dan vat)) cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach v ((nang ma) or (tang ma)) hoi. hieu va chet duoc va ((dan vai) OR (dan vat)) cua triet".
• Adding a wildcard symbol may retrieve word variants: te sach v ((nang ma) or (tang ma)) hoi. hieu va chet duoc va ((dan vai) OR (dan vat)) cua triet*.