Perhaps you should try some spelling variations:
dong hoc » dong co, dong luc
tan hanh » tan thanh, tang hanh, toan hanh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
dong ha » dong hoa, dong va, dong tai
van cam » van lam, van cau, van dam
hanh ca » hanh cac, hanh cat, hanh cua
cua tre » cua te, cuu tre, cua triet
ca cua » co cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((dong ha) OR (dong hoc)) hoi. hieu ((van cam) or (van nam)) duc tan hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((dong ha) OR (dong hoc)) hoi. hieu ((van cam) OR (van nam)) duc tan hanh ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((dong ha) OR (dong hoc)) hoi. hieu ((van cam) or (van nam)) duc tan hanh ca cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((dong ha) OR (dong hoc)) hoi. hieu ((van cam) or (van nam)) duc tan hanh ca cua tre*.