Perhaps you should try some spelling variations:
khoa doi » khoa hoi, khoa noi, khoan hoi
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
hanh tai » thanh tai, hang tai, han tai
va triet » va thiet, va trien, ve triet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
hoa doi » hoa dai, hoc doi, xoa doi
hieu he » hieu ve, hiem he, hieu le
he nam » ha nam, nghe nam
tai va » thai va, mai va, tri va

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 ((hoa doi) or (khoa doi)). hieu he nam thuc vat hanh tai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky dang ((hoa doi) OR (khoa doi)). hieu he nam thuc vat hanh tai va triet.
• Adding a wildcard symbol may retrieve word variants: su sach ky dang ((hoa doi) or (khoa doi)). hieu he nam thuc vat hanh tai va triet*.