Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, cay thuoc
nha thuoc » nha nuoc, nhan thuc, nha hoc
hieu van » hieu va, thien van, lieu va
tinh va » tich va, trinh van, trinh vat
va tinh » may tinh
su sach » so sach, vu sach
sang ma » tang ma, nang ma, sang tao
va cua » va chua, via cua, ca 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: su sach thieu ((sang ma) or (nang x)) hoi. hieu van ((nam thuoc) OR (nha thuoc)) va tinh va cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thieu ((sang ma) OR (nang x)) hoi. hieu van ((nam thuoc) OR (nha thuoc)) va tinh va cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach thieu ((sang ma) or (nang x)) hoi. hieu van ((nam thuoc) OR (nha thuoc)) va tinh va cua te".
• Adding a wildcard symbol may retrieve word variants: su sach thieu ((sang ma) or (nang x)) hoi. hieu van ((nam thuoc) OR (nha thuoc)) va tinh va cua te*.