Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
hanh va » hang va, hanh vi
hanh xa » hanh ma, hanh xu, canh xa
lam va » nam va, dam va, lam ha
nam ha » nam a, nam va, nam da
ve cam » ve cham, ve cac, va cam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thieu ((hanh xa) OR (hanh va)) hoi. hieu ve cam thuc va hanh ((lam va) or (nam ha)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thieu ((hanh xa) OR (hanh va)) hoi. hieu ve cam thuc va hanh ((lam va) OR (nam ha)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thieu ((hanh xa) OR (hanh va)) hoi. hieu ve cam thuc va hanh ((lam va) or (nam ha)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach thieu ((hanh xa) OR (hanh va)) hoi. hieu ve cam thuc va hanh ((lam va) or (nam ha)) triet*.