Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
lang tai » lang thai, hang tai, tang tai
cam thuc » am thuc, nam thuc, cam thu
cua tre » cua te, cuu tre, dua tren
va lang » va nang, hoa lang
thuc va » thuc vat, thuc dan, thuc day
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 ty hang ((x hoi) OR (o hoi)). hieu va cam thuc va lang tai ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty hang ((x hoi) OR (o hoi)). hieu va cam thuc va lang tai ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty hang ((x hoi) OR (o hoi)). hieu va cam thuc va lang tai ((cua tre) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: te sach ty hang ((x hoi) OR (o hoi)). hieu va cam thuc va lang tai ((cua tre) or (cua triet))*.