Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
minh cau » minh chau, sinh cau, minh can
dao minh » cao minh, van minh, duc minh
vien cac » vien bach, vien dai, vien da
sach ky » sach y, sach ty, sach kem
ve cac » va cac
sac ky » cac ky, sai ky
va dao » ca dao
x hoi » xa hoi, o hoi, x ho
su va » su van, tu va

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