Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
doan thi » dan thi, doanh tai, hoang thi
vat doan » van doan, van doanh, vay doanh
cam thuc » am thuc, nam thuc, cam thu
tu cach » tu cac
thi cua » thai cua, thi cuc, tri cua
hieu ve » hieu va, hieu van
van hoe » van hoa, van hoc, van hieu
van hoi » van hoa, van hoc, 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

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 hoe)). hieu ve cam thuc vat doan thi 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 hoe)). hieu ve cam thuc vat doan thi 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 hoe)). hieu ve cam thuc vat doan thi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (thu sach)) ky lang ((van hoi) OR (van hoe)). hieu ve cam thuc vat doan thi cua tre*.