Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
cau treo » cau theo, cau tren, cau triet
cua viet » ca viet, hoa viet, cua vat
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di

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