Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
thuoc ban » thuoc tan, thuoc dang, thu ban
ban hanh » ban hang
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
ve cuu » ve cau, ve cua, ve cum
ve chu » ve cau, ve che, ve cho
va chu » va che, va cau, va chi

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 ky nang mai hoi. hieu van nam thuoc ban hanh ((ve cuu) or (((ve chu) or (va chu)))) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang mai hoi. hieu van nam thuoc ban hanh ((ve cuu) OR (((ve chu) OR (va chu)))) tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang mai hoi. hieu van nam thuoc ban hanh ((ve cuu) or (((ve chu) or (va chu)))) tre*.