Perhaps you should try some spelling variations:
van thanh » ban thanh
nha thuoc » nha nuoc, nhan thuc, nha hoc
thu sach » thuat sach, thuoc sach, thu hoach
van tuan » van quan, van ban, anh tuan
nang mai » nang ma, nang tai, lang mai
tu sach » su sach, te sach, tu cach
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
y nang » ky nang, ly nang, v nang
vi nha » ve nha, va nha, li nha
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thu sach)) y nang mai hoi. hieu ve cac duc ((van thanh) OR (van tuan)) vi nha thuoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) y nang mai hoi. hieu ve cac duc ((van thanh) OR (van tuan)) vi nha thuoc*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) y nang mai hoi. hieu ve cac duc ((van thanh) OR (van tuan)) vi nha thuoc*".