Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
lang ha » long ha
lang xa » dang xay, lang van
sach ky » sac ky, sach y, sach ty
va cham » va chat, va tham
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
vai cau » va cau, van cau, vai cac
va dan » ca dan, va dao, va dau
va am » va lam, va cam

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 ky ((lang xa) or (lang ha)) hoi. hieu ((va am) or (va cham)) thuc va dan vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((lang xa) OR (lang ha)) hoi. hieu ((va am) OR (va cham)) thuc va dan vai cau tren.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((lang xa) or (lang ha)) hoi. hieu ((va am) or (va cham)) thuc va dan vai cau tren*.