Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
cua triet » su triet, va triet
hieu van » hieu va, thien van, lieu va
cua viet » ca viet, hoa viet, cua vat
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
thuc va » thuc vat, thuc dan, thuc day
tuc va » truc va, tuc xa, duc va

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

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