Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hanh vai » hanh vi, hanh va, hanh tai
cau tren » cu tren, dau tren, ca tren
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
nang ma » tang ma, sang ma, nang cao
vai cau » va cau, van cau, vai cac
va nam » van nam, ha nam, va nay
ve nam » he nam, le nam, te nam

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

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