Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » hieu va, thien van, lieu va
dau truc » cau truc, dai truc, doan truc
va thanh » gia thanh, ban thanh, va tinh
sach ky » sac ky, sach y, sach ty
cao hoc » co hoc, cho hoc, chat hoc
van dau » van dao, phan dau
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cuu tre, cua triet

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 ky) or (cac ky)) nang cao hoc. hieu van dau truc va thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (cac ky)) nang cao hoc. hieu van dau truc va thanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (cac ky)) nang cao hoc. hieu van dau truc va thanh dai cua tre*.