Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam ngoc » lam ngoc, pham ngoc, van ngoc
so sach » so sanh, bo sach, co sach
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
van hoc » van hoa
va hanh » van hanh, va thanh, va danh
vi cua » vai cua, di cua
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: so sach ((ky lang) OR (ky dang)) xa hoi. hieu van ((nam ngoc) or (van hoc)) va hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky lang) OR (ky dang)) xa hoi. hieu van ((nam ngoc) OR (van hoc)) va hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky lang) OR (ky dang)) xa hoi. hieu van ((nam ngoc) or (van hoc)) va hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky lang) OR (ky dang)) xa hoi. hieu van ((nam ngoc) or (van hoc)) va hanh vi cua te*.