Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
toc sach » hoc sach, doc sach, thuoc sach
van hieu » cao hieu
vat hanh » vat thanh, van hanh, va hanh
van hoi » van hoc, van hoe, van loi
hieu ve » hieu va, hieu van
ve tham » va tham, ve cham, vi tham
hanh di » hanh vi, hanh de, hang di
di cua » dai cua, doi cua, de cua
cua te » cua tu

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 _ lang ((van hoi) or (((van hieu) or (van hoa)))). hieu ve tham thuc vat hanh di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach _ lang ((van hoi) OR (((van hieu) OR (van hoa)))). hieu ve tham thuc vat hanh di cua te.
• Adding a wildcard symbol may retrieve word variants: toc sach _ lang ((van hoi) or (((van hieu) or (van hoa)))). hieu ve tham thuc vat hanh di cua te*.