Perhaps you should try some spelling variations:
sach kho » bach khoa, sach nha, sach kem
vat hanh » vat thanh, van hanh, va hanh
hieu van » hieu va, thien van, lieu va
tang hat » tang ha, dang hat, lang hat
sach dao » lanh dao
hat doi » hoat doi, thay doi, hang doi
thu vat » thuc vat, thu va, thuat vat
vai su » va su, lai su, tai su
van su » dan su

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 kho) or (sach dao)) tang hat doi. hieu van nam thu vat hanh ((vai su) or (van su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach kho) OR (sach dao)) tang hat doi. hieu van nam thu vat hanh ((vai su) OR (van su)) triet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach kho) or (sach dao)) tang hat doi. hieu van nam thu vat hanh ((vai su) or (van su)) triet*.