Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
luu tre » luu tru, cuu tre, luy tre
sang ma » sang tao, mang may, sang tai
nang ma » nang cao, mang may
va cam » va cham, va cac, va cao
xuc va » duc va, tuc va, luc va
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi luu » vi lua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y ((nang ma) OR (((sang ma) OR (tang ma)))) hoi. hieu va cam xuc va dan vi luu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y ((nang ma) or (((sang ma) OR (tang ma)))) hoi. hieu va cam xuc va dan vi luu tre~".
• Adding a wildcard symbol may retrieve word variants: doc sach y ((nang ma) or (((sang ma) OR (tang ma)))) hoi. hieu va cam xuc va dan vi luu tre*.