Perhaps you should try some spelling variations:
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
hieu va » lieu va, hieu qua
va tinh » may tinh
tinh di » tinh doi, trinh di, tinh da
cua tre » cua te, cuu tre, cua triet
cac su » cach su, cac sau, cac du
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho
su va » su van, tu va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ty) or (sach tu)) nang x hoi. hieu va cac su va tinh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ty) OR (sach tu)) nang x hoi. hieu va cac su va tinh di cua tre.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ty) or (sach tu)) nang x hoi. hieu va cac su va tinh di cua tre*.