Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
va kinh » va tinh, qua kinh
va dinh » van dinh, va tinh, vu dinh
hieu va » lieu va, hieu qua
ly nang » ky nang, ly hang, ly vang
su viet » so viet
ma hoi » mai hoi, xa hoi, ma hoa
y nang » ky nang, v nang, may nang
va dao » ca dao
dao tu » dao tuc, dao tru, tao tu

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 ((y nang) OR (ly nang)) ma hoi. hieu va dao tu ((va dinh) or (va kinh)) va su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((y nang) OR (ly nang)) ma hoi. hieu va dao tu ((va dinh) OR (va kinh)) va su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((y nang) OR (ly nang)) ma hoi. hieu va dao tu ((va dinh) or (va kinh)) va su viet".
• Adding a wildcard symbol may retrieve word variants: doc sach ((y nang) OR (ly nang)) ma hoi. hieu va dao tu ((va dinh) or (va kinh)) va su viet*.