Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach nay » sach hay, sach vay, sach nang
lang mai » lang dai, lang hai, lang man
dau tren » dau tien, dat tren, dau tieng
lang ma » lang man, lang ha, tang ma
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
xa hanh » xa thanh, xa khanh, va hanh
vi dau » vi dai, va dau, bi dau

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 nay ((lang ma) or (lang mai)) hoi. hieu va cac tuc xa hanh vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach nay ((lang ma) OR (lang mai)) hoi. hieu va cac tuc xa hanh vi dau tren.
• Adding a wildcard symbol may retrieve word variants: toc sach nay ((lang ma) or (lang mai)) hoi. hieu va cac tuc xa hanh vi dau tren*.