Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
truc may » tren may, truc va
hoc sach » hoc sinh, hoc cac, hoc anh
cac truc » cau truc, cac tru, cac trung
nang van » dang van, tang van, lang van
su sach » so sach, vu sach
tinh va » tich va, trinh van, trinh vat
hieu ve » hieu va, hieu van
van hoi » van hoa, van hoc, van hoe
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) OR (hoc sach)))) ky nang van hoi. hieu ve cac truc may tinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (((toc sach) OR (hoc sach)))) ky nang van hoi. hieu ve cac truc may tinh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (((toc sach) OR (hoc sach)))) ky nang van hoi. hieu ve cac truc may tinh va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (((toc sach) OR (hoc sach)))) ky nang van hoi. hieu ve cac truc may tinh va cua tre*.