Perhaps you should try some spelling variations:
nam duoc » nam thuoc, da duoc, dat duoc
van hanh » van thanh, ban hanh, van anh
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cua tre » cuu tre, cua triet, dua tren
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang xa hoi. hieu va ((nam duoc) or (pham duc)) van hanh vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang xa hoi. hieu va ((nam duoc) OR (pham duc)) van hanh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang xa hoi. hieu va ((nam duoc) or (pham duc)) van hanh vi ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang xa hoi. hieu va ((nam duoc) or (pham duc)) van hanh vi ((cua tre) OR (cua te))*.