Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang van » dang van, tang van, lang van
cac thuc » cach thuc, cac thu, can thuc
thuc may » thuc day, truc may, phuc may
su sach » so sach, vu sach
van hoi » van hoa, van hoc, van hoe
hieu ve » hieu va, hieu van
tinh va » tich va, trinh van, trinh vat
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
va cua » va chua, via cua, ca cua

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 (toc sach)) ky nang van hoi. hieu ve cac thuc may tinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (toc sach)) ky nang van hoi. hieu ve cac thuc may tinh va cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (toc sach)) ky nang van hoi. hieu ve cac thuc may tinh va cua tre*.