Perhaps you should try some spelling variations:
chet duoc » che duoc, cho duoc, che quoc
cua triet » cua viet, su triet, va triet
te sach » toc sach
duoc va » nuoc va, duc va, duoc ma
su viet » so viet
va chet » va chiet, va che, va chat
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
sach v » sach va, sach y, sach 2
dan vi » doan vi, dan va, gan vi
v nang » va nang, vu nang, van nang

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