Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
hieu va » lieu va, hieu qua
dan dai » dat dai, can dai, dan dat
cao luc » bao luc, cao duc, cao suc
nang ro » nang co, nang ho, nang ra
va dan » ca dan, va dao, va dau
luc va » duc va, tuc va, loc va
va cao » va cac, va co, va dao
nang o » nang co, nang ho, nang x
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: ((toc sach) or (thuoc sach)) v ((nang o) OR (nang ro)) hoi. hieu va cao luc va dan dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) v ((nang o) OR (nang ro)) hoi. hieu va cao luc va dan dai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (thuoc sach)) v ((nang o) OR (nang ro)) hoi. hieu va cao luc va dan dai cua te*".