Perhaps you should try some spelling variations:
cua thuoc » nha thuoc, cay thuoc, cua nuoc
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
ve cac » va cac, vien cac
cua tu » cua tuc, cua su, cua cu

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 ky ((mang may) or (nang cao)) hoi. hieu ve cac duc van hanh vi ((cua tu) or (cua thuoc))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((mang may) OR (nang cao)) hoi. hieu ve cac duc van hanh vi ((cua tu) OR (cua thuoc)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((mang may) or (nang cao)) hoi. hieu ve cac duc van hanh vi ((cua tu) or (cua thuoc))*.