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

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. hieu ((va cam) OR (va cao)) 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. hieu ((va cam) OR (va cao)) 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. hieu ((va cam) OR (va cao)) thuc va dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (thu sach)) ky lang van hoi. hieu ((va cam) OR (va cao)) thuc va dan vi cua tre*.