Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
cac thuc » cach thuc, cac thu, can thuc
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van cac » van hac, van cau, van bac
thuc va » thuc vat, thuc dan, thuc day
va dinh » van dinh, va kinh, va tinh
dinh di » dinh du, dinh vi, danh di
cua tre » cua te, cuu tre, dua tren

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (cac ky)) nang xa hoi. hieu van cac thuc va dinh di ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (cac ky)) nang xa hoi. hieu van cac thuc va dinh di ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (cac ky)) nang xa hoi. hieu van cac thuc va dinh di ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (cac ky)) nang xa hoi. hieu van cac thuc va dinh di ((cua tre) OR (cua triet))*.