Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
cac tu » cac thu, cach tu, cac du
va dan » ca dan, va dao, va dau
ca cau » cua cau, cac cau, can cau

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) or (thu sach)) ky nang cao hoi. hieu ve cac tu va dan ca cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (thu sach)) ky nang cao hoi. hieu ve cac tu va dan ca cau tren.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (thu sach)) ky nang cao hoi. hieu ve cac tu va dan ca cau tren*.