Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach tay » xach tay, sach hay, sach nay
trung ma » trung ha, trung va, trung cap
cam thuc » am thuc, nam thuc, cam thu
dau tren » dau tien, dat tren, dau tieng
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
va cam » va cham, va cac, va cao
va dau » va dao

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 tay ((trung ma) or (trung tam)) hoi. hieu va cam thuc va hanh va dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tay ((trung ma) OR (trung tam)) hoi. hieu va cam thuc va hanh va dau tren.
• Adding a wildcard symbol may retrieve word variants: toc sach tay ((trung ma) or (trung tam)) hoi. hieu va cam thuc va hanh va dau tren*.