Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cua viet » ca viet, hoa viet, cua vat
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
hieu v » hieu va, hieu ve, hieu 2
v pham » vi pham, d pham
x hoi » xa hoi, o hoi, x ho

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 v pham duc va hanh di ((cau tren) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ty) OR (sach tu)) nang x hoi. hieu v pham duc va hanh di ((cau tren) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ty) OR (sach tu)) nang x hoi. hieu v pham duc va hanh di ((cau tren) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ty) OR (sach tu)) nang x hoi. hieu v pham duc va hanh di ((cau tren) or (cua viet))*.