Perhaps you should try some spelling variations:
hanh vit » hanh vi, danh viet, hanh tiet
thuc day » thuc vat
thuc dan » thuc hanh, hoc dan, thuc vat
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ca viet » va viet, co viet, hoa viet
hieu ve » hieu va, hieu van
ty tang » tay tang, ty xang, ty hang
me hoi » le hoi
vit ca » viet ca, viet cau
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: su sach ty tang ((me hoi) or (xa hoi)). hieu ve nam ((thuc dan) or (thuc day)) hanh vit ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty tang ((me hoi) OR (xa hoi)). hieu ve nam ((thuc dan) OR (thuc day)) hanh vit ca viet.
• Adding a wildcard symbol may retrieve word variants: su sach ty tang ((me hoi) or (xa hoi)). hieu ve nam ((thuc dan) or (thuc day)) hanh vit ca viet*.