Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va hanh » van hanh, va thanh, va danh
hieu va » hieu qua
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
sach v » sach va, sach y, sach 2
xuc va » duc va, tuc va, luc va
v nang » va nang, vu nang, van nang
di bo » doi bo, do bo, de bo
di o » do o, oi o

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach v nang ma hoi. ((hieu va) or (lieu va)) cam xuc va hanh ((di bo) OR (di o)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v nang ma hoi. ((hieu va) OR (lieu va)) cam xuc va hanh ((di bo) OR (di o)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach v nang ma hoi. ((hieu va) or (lieu va)) cam xuc va hanh ((di bo) OR (di o)) triet".
• Adding a wildcard symbol may retrieve word variants: toc sach v nang ma hoi. ((hieu va) or (lieu va)) cam xuc va hanh ((di bo) OR (di o)) triet*.