Perhaps you should try some spelling variations:
nam thuoc » nam thu, nha thuoc, cay thuoc
van viet » san viet, gian viet, tran viet
van hanh » van thanh, ban hanh, van anh
nam thuc » am thuc, nam thu, nam tu
hanh va » hang va, hanh vi
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
hieu le » hieu ve, hieu he, hieu ly
me hoi » le hoi

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

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