Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
doc sach » hoc sach, nuoc sach, dac sac
hieu ve » hieu va, hieu van
cao tao » dao tao, cao tai, cau tao
ky sang » ky nang, ky dang, ky tang
ma hoi » mai hoi, xa hoi, me hoi
ve cac » va cac, vien cac
va dau » va dao
dau va » dau ve, lau va
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (doc sach)) ky sang ((ma hoi) or (ma hoa)). hieu ve cac nuoc va dau va cao tao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky sang ((ma hoi) OR (ma hoa)). hieu ve cac nuoc va dau va cao tao.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ky sang ((ma hoi) or (ma hoa)). hieu ve cac nuoc va dau va cao tao*.