Perhaps you should try some spelling variations:
nhan thuc » nhan luc, dan thuc, toan thuc
nang mai » nang ma, nang tai, lang mai
hanh di » hanh de, hang di, danh di
ve nhan » ve nha, de nhan, va nhan
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
sai ky » sac ky

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 ky) or (sai ky)) nang mai hoi. hieu ve nhan thuc vat ((hanh di) OR (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sai ky)) nang mai hoi. hieu ve nhan thuc vat ((hanh di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sai ky)) nang mai hoi. hieu ve nhan thuc vat ((hanh di) OR (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sai ky)) nang mai hoi. hieu ve nhan thuc vat ((hanh di) OR (hanh vi)) cua tre*.