Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, hinh tai
cao hoc » co hoc, cho hoc, chat hoc
han tai » hang tai, nhan tai, van tai
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y nang cao hoc. hieu van ((hoc nuoc) or (dat nuoc)) ban ((hanh tai) OR (han tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang cao hoc. hieu van ((hoc nuoc) OR (dat nuoc)) ban ((hanh tai) OR (han tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang cao hoc. hieu van ((hoc nuoc) or (dat nuoc)) ban ((hanh tai) OR (han tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang cao hoc. hieu van ((hoc nuoc) or (dat nuoc)) ban ((hanh tai) OR (han tai)) cua tre*.