Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
thanh da » thanh dat, thanh dam, thanh dan
dau tren » dau tien, dat tren, dau tieng
so sach » so sanh, bo sach, co sach
mai hoi » mai khoi, dai hoi, lai hoi
soc gia » hoc gia, so gia, quoc gia
toc gia » toc giay, tac gia, quoc gia
y nang » ky nang, ly nang, v nang
da dau » dan dau, dat dau, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y nang mai hoi. hieu van cham ((soc gia) or (toc gia)) thanh da dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang mai hoi. hieu van cham ((soc gia) OR (toc gia)) thanh da dau tren.
• Adding a wildcard symbol may retrieve word variants: so sach y nang mai hoi. hieu van cham ((soc gia) or (toc gia)) thanh da dau tren*.