Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
cuu tre » cua tre, cau tren, cau treo
ve cac » va cac
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao
vi cuu » vi luu, vinh cuu
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)) tu ((va dan) OR (ca dan)) vi cuu tre~.
• 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)) tu ((va dan) OR (ca dan)) vi cuu tre.
• 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)) tu ((va dan) OR (ca dan)) vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu ((ve cac) or (vien cac)) tu ((va dan) OR (ca dan)) vi cuu tre*.