Perhaps you should try some spelling variations:
va thieu » va thiet, va hieu, va tieu
cam thuc » am thuc, nam thuc, cam thu
va triet » va thiet, va trien, ve triet
day hanh » day nhanh, day thanh, dao hanh
thuc day » thuc dan, thuc vat
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
tay hoi » tay ho, tao hoi, tay thai
hoi van » hoi dan, hai van, hoi han
van cam » van nam, van lam, van cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((hoi van) OR (hoi va)) tay hoi. hieu van cam thuc day hanh vi ((va triet) or (va thieu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((hoi van) OR (hoi va)) tay hoi. hieu van cam thuc day hanh vi ((va triet) OR (va thieu))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((hoi van) OR (hoi va)) tay hoi. hieu van cam thuc day hanh vi ((va triet) or (va thieu))*".