Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van giao » nang giao, toan giao, dan gian
cau theo » cau thi, cau tao
tu sach » thu sach, su sach, te sach
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
cuu tre » cua tre, cau tren, cau treo

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 ((nang xa) or (nang ma)) hoi. hieu van giao duc va hanh vi ((cuu tre) or (cau theo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van giao duc va hanh vi ((cuu tre) OR (cau theo)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. hieu van giao duc va hanh vi ((cuu tre) or (cau theo))*.