Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dan thai » dang thai, dan thi, dan than
thai cau » thai cao, toan cau, thai van
cau treo » cau theo, cau tren, cau triet
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
van dau » phan dau
va dan » ca dan, va dao, 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: ((te sach) OR (toc sach)) ky lang xa hoi. hieu ((van dau) or (van dao)) nuoc va dan thai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang xa hoi. hieu ((van dau) OR (van dao)) nuoc va dan thai cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky lang xa hoi. hieu ((van dau) or (van dao)) nuoc va dan thai cau treo".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky lang xa hoi. hieu ((van dau) or (van dao)) nuoc va dan thai cau treo*.