Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
sach dao » lanh dao
tang van » dang van, hoang van, trong van
su sach » so sach, vu sach
cao anh » cao dang, cao tang, cao bang
va tham » van tham, va cham, va thanh
nang ma » tang ma, sang ma, nang cao
di cua » dai cua, doi cua, de cua
cua su » qua su

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 dao ((nang ma) or (tang van)) hoi. lieu va tham thuc ((cao anh) or (suc manh)) di cua su~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach dao ((nang ma) OR (tang van)) hoi. lieu va tham thuc ((cao anh) OR (suc manh)) di cua su.
• Adding a wildcard symbol may retrieve word variants: su sach dao ((nang ma) or (tang van)) hoi. lieu va tham thuc ((cao anh) or (suc manh)) di cua su*.