Perhaps you should try some spelling variations:
sinh cau » trinh cau, sinh vat, sinh va
vinh cau » vinh cuu, minh cau, tinh cau
sach thu » sach thue, sach thieu, sach tham
lang mai » lang dai, lang hai, lang man
cac toc » cac toi, cac nuoc, cac thoi
sach ty » sach y, sach tu, xach tay
mai hoi » mai khoi, dai hoi, lai hoi
qua cac » cua cac
toc ca » toc cao, toc ta, toc co

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 ty) or (sach thu)) lang mai hoi. hieu qua cac toc ca dao ((vinh cau) OR (sinh cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach thu)) lang mai hoi. hieu qua cac toc ca dao ((vinh cau) OR (sinh cau)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) or (sach thu)) lang mai hoi. hieu qua cac toc ca dao ((vinh cau) OR (sinh cau)) tren".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach thu)) lang mai hoi. hieu qua cac toc ca dao ((vinh cau) OR (sinh cau)) tren*.