Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
thuc day » thuc dan, thuc vat
day hanh » day nhanh, day thanh, dao hanh
hanh vai » hanh vi, hanh va, hanh tai
nang ma » tang ma, sang ma, mang may
hieu ve » hieu va, hieu van
ca tren » cau tren, cu tren, la tren
ve nam » he nam, va nam, le nam
vai ca » vai cac, vai cua, bai ca

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 y ((((nang ma) OR (nang cao))) or (nang x)) hoi. hieu ve nam thuc day hanh vai ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((((nang ma) OR (nang cao))) OR (nang x)) hoi. hieu ve nam thuc day hanh vai ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((((nang ma) OR (nang cao))) or (nang x)) hoi. hieu ve nam thuc day hanh vai ca tren".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((((nang ma) OR (nang cao))) or (nang x)) hoi. hieu ve nam thuc day hanh vai ca tren*.