Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
van phat » va phat, van chat, van phan
phat dua » phat cua, hat dua, phan dua
thanh ve » hanh ve, thanh va, thanh vien
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
dua ban » dia ban, cua ban, qua ban
su viet » so viet
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky lang xa hoi. hieu van phat dua ban thanh ve ((su viet) or (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky lang xa hoi. hieu van phat dua ban thanh ve ((su viet) OR (hoa viet)).
• Adding a wildcard symbol may retrieve word variants: tu sac ky lang xa hoi. hieu van phat dua ban thanh ve ((su viet) or (hoa viet))*.