Perhaps you should try some spelling variations:
quoc giao » quoc gia, nuoc giao, duoc giao
giao hanh » giao thanh, gia hanh, gian thanh
hieu van » hieu va, thien van, lieu va
su triet » su viet, ve triet
cam quoc » cac quoc, cao quoc, nam quoc
van cam » van nam, van lam, van cau
hanh va » hang va, hanh vi
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
sang ma » tang ma, nang ma, sang tao
nang xa » nang x, lang xa, nang ma
su tien » su kien, su hien, tu tieng

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty ((nang xa) or (sang ma)) hoi. hieu van cam quoc giao hanh va ((su triet) OR (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (sang ma)) hoi. hieu van cam quoc giao hanh va ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (sang ma)) hoi. hieu van cam quoc giao hanh va ((su triet) OR (su tien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (sang ma)) hoi. hieu van cam quoc giao hanh va ((su triet) OR (su tien))*.