Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
van hanh » ban hanh, van anh, van ban
khoa hoi » khoan hoi, khoa hoc, khoa doi
su sach » so sach, vu sach
hieu le » hieu ve, hieu he, hieu ly
sach ky » sac ky, sach y, sach ty
hoa hoi » hoa hoc, hoa doi, hoc hoi
ky lang » ky nang, ky dang, ky tang
su viet » so viet
le nam » ly nam, he nam, le na
vai su » va su, van su, lai su

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 lang ((hoa hoi) or (khoa hoi)). hieu le nam thu ((van hanh) or (van thanh)) vai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky lang ((hoa hoi) OR (khoa hoi)). hieu le nam thu ((van hanh) OR (van thanh)) vai su viet.
• Adding a wildcard symbol may retrieve word variants: su sach ky lang ((hoa hoi) or (khoa hoi)). hieu le nam thu ((van hanh) or (van thanh)) vai su viet*.