Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cao khoa » lao khoa, bao khoa, cac khoa
hanh tai » thanh tai, han tai, hinh tai
hang tai » hang va, dung tai
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cuc tre » duc tre, cua tre, cuu tre
va cao » va cac, va co, va dao
xuc va » tuc va, luc va, xac va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty nang cao khoa. lieu va cao ((xuc va) OR (duc va)) ((hanh tai) or (hang tai)) cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang cao khoa. lieu va cao ((xuc va) OR (duc va)) ((hanh tai) OR (hang tai)) cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang cao khoa. lieu va cao ((xuc va) OR (duc va)) ((hanh tai) or (hang tai)) cuc tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang cao khoa. lieu va cao ((xuc va) OR (duc va)) ((hanh tai) or (hang tai)) cuc tre*.