Perhaps you should try some spelling variations:
cach thuc » anh thuc
vat luan » vay luan, dat luan, van luan
cau tren » cu tren, dau tren, ca tren
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty lang » tay lang, ty xang, ty hang
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
cac thu » cac thuat, cac thoi
luan vi » quan vi, luan va, luan ve
vi cau » va cau, ve cau, di cau

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 lang xa hoi. hieu ve ((cach thuc) OR (cac thu)) vat luan vi cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty lang xa hoi. hieu ve ((cach thuc) OR (cac thu)) vat luan vi cau tren".
• Adding a wildcard symbol may retrieve word variants: te sach ty lang xa hoi. hieu ve ((cach thuc) OR (cac thu)) vat luan vi cau tren*.