Perhaps you should try some spelling variations:
lang van » dang van, tang van, hoang van
lang xa » lang ha, dang xay
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac toc » cac toi, cac nuoc, cac thoi
xa dong » ha dong, van dong, lao dong
su sach » so sach, vu sach
ve cac » va cac, vien cac
thiet » thieu

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 xa) or (lang van)) hoi. hieu ve cac toc ((xa dong) or (cam nang)) hoi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((lang xa) OR (lang van)) hoi. hieu ve cac toc ((xa dong) OR (cam nang)) hoi va thiet.
• Adding a wildcard symbol may retrieve word variants: su sach ky ((lang xa) or (lang van)) hoi. hieu ve cac toc ((xa dong) or (cam nang)) hoi va thiet*.