Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
cua viet » ca viet, hoa viet, cua vat
te sach » toc sach
ky tang » ky nang, ky dang, kho tang
thuc va » thuc vat, thuc dan, thuc day
va lanh » va lang, va danh, va hanh
dao cua » dai cua, day cua, dan cua
y tang » 6 tang, 7 tang, 5 tang
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((y tang) or (ky tang)) ma hoi. hieu van cham thuc va lanh dao cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((y tang) OR (ky tang)) ma hoi. hieu van cham thuc va lanh dao cua viet.
• Adding a wildcard symbol may retrieve word variants: te sach ((y tang) or (ky tang)) ma hoi. hieu van cham thuc va lanh dao cua viet*.