Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
sach tay » xach tay, sach hay, sach nay
cam thuc » am thuc, nam thuc, cam thu
cau tren » cu tren, dau tren, ca tren
tang ma » tang van
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va hang » van hang, va nang, va lang
va cam » va cham, va cac, va cao
va cau » van cau, va cac, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach tay ((tang ma) OR (mang may)) hoi. hieu va cam thuc va hang va cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach tay ((tang ma) OR (mang may)) hoi. hieu va cam thuc va hang va cau tren".
• Adding a wildcard symbol may retrieve word variants: doc sach tay ((tang ma) OR (mang may)) hoi. hieu va cam thuc va hang va cau tren*.