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

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) OR (bo sach)) ky dang mai hoi. hieu ve 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) OR (bo sach)) ky dang mai hoi. hieu ve nam thuc ((va danh) OR (va thanh)) vi hoc viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) OR (bo sach)) ky dang mai hoi. hieu ve nam thuc ((va danh) or (va thanh)) vi hoc viet".
• Adding a wildcard symbol may retrieve word variants: ((so sach) OR (bo sach)) ky dang mai hoi. hieu ve nam thuc ((va danh) or (va thanh)) vi hoc viet*.