Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
va cam » va cham, va cac, va cao
vi cua » vai cua, di cua
ve cam » ve cham, ve cac, ve 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 sach y ((nang ma) or (tang ma)) hoi. hieu ((ve cam) or (va cam)) thuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang ma) OR (tang ma)) hoi. hieu ((ve cam) OR (va cam)) thuc van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) or (tang ma)) hoi. hieu ((ve cam) or (va cam)) thuc van hanh vi cua tre*.