Perhaps you should try some spelling variations:
thieu nien » thien nhien
hieu vien » hieu hien, hieu viec, hieu tieng
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
cac dai » cac dan, cac bai, can dai
ky dang » ky nang, ky danh
ky sang » ky nang, ky tang, duy sang
dai va » mai va
cua te » cua tu

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 sang) OR (ky dang)) ma hoa. ((hieu vien) or (thieu nien)) cac dai va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky sang) OR (ky dang)) ma hoa. ((hieu vien) OR (thieu nien)) cac dai va hanh tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky sang) OR (ky dang)) ma hoa. ((hieu vien) or (thieu nien)) cac dai va hanh tai cua te".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky sang) OR (ky dang)) ma hoa. ((hieu vien) or (thieu nien)) cac dai va hanh tai cua te*.