Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc day » thuc dan, thuc vat
tay lang » tai lang, tay tang, tay quang
cau tren » cu tren, dau tren, cau treo
sach tay » xach tay, sach hay, sach nay
dan vai » dan va, dan tai, dan vat
ca tren » cu tren, la tren, co tren
thuc va » thuc vat, thuc dan
hieu ha » hieu hoa, hieu va, hieu ca
lang xa » lang ha, dang xay, lang van

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 lang xa hoi. hieu ha nam ((thuc va) OR (thuc day)) dan vai ((cau tren) or (ca tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tay lang xa hoi. hieu ha nam ((thuc va) OR (thuc day)) dan vai ((cau tren) OR (ca tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tay lang xa hoi. hieu ha nam ((thuc va) OR (thuc day)) dan vai ((cau tren) or (ca tren))".
• Adding a wildcard symbol may retrieve word variants: toc sach tay lang xa hoi. hieu ha nam ((thuc va) OR (thuc day)) dan vai ((cau tren) or (ca tren))*.