Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hoa lang » hoa dan, hoa van
va trien » va truyen, va thiet, va tuyen
hoc cac » hoc cao
lang xa » lang ha, dang xay, lang van
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
hieu va » hieu qua
xuc va » duc va, tuc va, luc va
di va » dai va, di vao, doi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc sach) or (hoc cac)) hoa lang xa hoi. ((hieu va) or (lieu va)) cam xuc va hanh di va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (hoc cac)) hoa lang xa hoi. ((hieu va) OR (lieu va)) cam xuc va hanh di va trien.
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (hoc cac)) hoa lang xa hoi. ((hieu va) or (lieu va)) cam xuc va hanh di va trien*.