Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
toc sach » hoc sach, doc sach, thuoc sach
vat hanh » vat thanh, van hanh, va hanh
hieu ve » hieu va, hieu van
ve tham » va tham, ve cham, vi tham
so sach » so sanh, bo sach, co sach
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
ha hoi » hoa hoi, ha noi, xa hoi
di cua » doi cua, de cua, do cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (toc sach)) ky lang ha hoi. hieu ve tham thuc vat hanh ((di cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (toc sach)) ky lang ha hoi. hieu ve tham thuc vat hanh ((di cua) OR (dai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (toc sach)) ky lang ha hoi. hieu ve tham thuc vat hanh ((di cua) or (dai cua)) tre*.