Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet

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