Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
nang van » dang van, tang van, lang van
cac thuc » cach thuc, cac thu, can thuc
thuc day » thuc dan, thuc vat
day tinh » may tinh, dac tinh, dao tinh
su sach » so sach, vu sach
tinh va » tich va, trinh van, trinh vat
cua tre » cuu tre, cua triet, dua tren
van hoi » van hoa, van hoc, van hoe
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
cua te » cua tu

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