Perhaps you should try some spelling variations:
dang mai » dang hai, dang mau, dang bai
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
va thanh » gia thanh, ban thanh, va tinh
hoc viet » hoc hien
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
mai hoi » mai khoi, dai hoi, lai hoi
va danh » va dinh, va dan, va hanh
vi hoc » li hoc, va hoc

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 ky dang mai hoi. hieu van nam thuc ((va danh) or (va thanh)) vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky dang mai hoi. hieu van nam thuc ((va danh) OR (va thanh)) vi hoc viet.
• Adding a wildcard symbol may retrieve word variants: so sach ky dang mai hoi. hieu van nam thuc ((va danh) or (va thanh)) vi hoc viet*.