Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cam thuc » am thuc, nam thuc, cam thu
tu cach » tu cac
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
van hoc » van hoa
van hoi » van hoa, van hoe, van loi
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (thu sach)) ky lang ((van hoi) OR (van hoc)). hieu ve cam thuc va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (thu sach)) ky lang ((van hoi) OR (van hoc)). hieu ve cam thuc va dan vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (thu sach)) ky lang ((van hoi) OR (van hoc)). hieu ve cam thuc va dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (thu sach)) ky lang ((van hoi) OR (van hoc)). hieu ve cam thuc va dan vi cua tre*.