Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
nam thuc » nam thuoc, am thuc, nam thu
bo sach » co sach, hoc sach
va hanh » van hanh, va danh, ban hanh
ky mang » ky nang, ke mang, ky dang
may hoi » may thoi, mai hoi, may hmi
tay hoi » tay ho, tao hoi, tay thai
hieu he » hieu ve, hiem he, hieu le
sach ky » sac ky, sach y, sach ty
he nam » ha nam, nghe nam
vi hoa » voi hoa, vi hoc, va hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo sach ky mang ((may hoi) OR (tay hoi)). hieu he nam thuc ((va hanh) or (va thanh)) vi hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo sach ky mang ((may hoi) OR (tay hoi)). hieu he nam thuc ((va hanh) OR (va thanh)) vi hoa viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo sach ky mang ((may hoi) OR (tay hoi)). hieu he nam thuc ((va hanh) or (va thanh)) vi hoa viet".
• Adding a wildcard symbol may retrieve word variants: bo sach ky mang ((may hoi) OR (tay hoi)). hieu he nam thuc ((va hanh) or (va thanh)) vi hoa viet*.