Perhaps you should try some spelling variations:
can thiet » dan thiet, cac thiet, cad thiet
ban hanh » ban hang
su sach » so sach, vu sach
sach lo » sach dao, sach doi, sach hoi
lo nang » ho nang, ly nang, loai nang
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cau luc » cau phuc
va danh » va dinh, va dan, va hanh
vi can » voi can, vi van, i can

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach lo nang ma hoa. hieu va ((cau luc) or (cau truc)) ((va danh) or (ban hanh)) vi can thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach lo nang ma hoa. hieu va ((cau luc) OR (cau truc)) ((va danh) OR (ban hanh)) vi can thiet.
• Adding a wildcard symbol may retrieve word variants: su sach lo nang ma hoa. hieu va ((cau luc) or (cau truc)) ((va danh) or (ban hanh)) vi can thiet*.