Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
minh can » minh chanh, minh danh, minh tuan
minh cau » minh chau, sinh cau, minh cac
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
va dao » ca dao
ve cac » va cac
su va » su van, tu va
x hoi » xa hoi, o hoi, x ho

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 ky nang x hoi. hieu ((ve cac) or (vien cac)) su va dao ((minh cau) OR (minh can)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu ((ve cac) OR (vien cac)) su va dao ((minh cau) OR (minh can)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu ((ve cac) or (vien cac)) su va dao ((minh cau) OR (minh can)) tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu ((ve cac) or (vien cac)) su va dao ((minh cau) OR (minh can)) tren*.