Perhaps you should try some spelling variations:
nhat hanh » nhat ban, nhat minh
dang khoa » dung khoa, hang khoa, dang khoi
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam tu
su triet » su viet, su tien, ve triet
khoa hoi » khoan hoi, khoa hoc, khoa doi
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
ty dang » ty xang, ky dang, ty hang
va hanh » van hanh, va thanh, va danh
ve su » va su

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 ty dang khoa hoi. hieu ve ((nam thuc) or (nam thu)) ((nhat hanh) or (va hanh)) ve su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty dang khoa hoi. hieu ve ((nam thuc) OR (nam thu)) ((nhat hanh) OR (va hanh)) ve su triet.
• Adding a wildcard symbol may retrieve word variants: toc sach ty dang khoa hoi. hieu ve ((nam thuc) or (nam thu)) ((nhat hanh) or (va hanh)) ve su triet*.