Perhaps you should try some spelling variations:
ban hanh » ban hang
sach vay » sach va, sach hay, sach nay
va trien » va truyen, va thiet, va tuyen
nang mai » nang ma, nang tai, lang mai
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » hieu qua
cam duc » cam xuc, cao duc, pham duc
duc ban » duc tan, duc van, dua ban
hanh di » hanh vi, hanh de, hang di
di va » dai va, di vao, doi va

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 vay) or (sach y)) nang mai hoi. ((hieu va) or (lieu va)) cam duc ban hanh di va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach vay) OR (sach y)) nang mai hoi. ((hieu va) OR (lieu va)) cam duc ban hanh di va trien.
• Adding a wildcard symbol may retrieve word variants: toc ((sach vay) or (sach y)) nang mai hoi. ((hieu va) or (lieu va)) cam duc ban hanh di va trien*.