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

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. hieu va cam ((thuc vat) or (thuc dan)) 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. hieu va cam ((thuc vat) OR (thuc dan)) 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. hieu va cam ((thuc vat) or (thuc dan)) lang tai ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: te sach ty hang x hoi. hieu va cam ((thuc vat) or (thuc dan)) lang tai ((cua tre) OR (cua triet))*.