Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
khoa hoc » hoa hoc
thu nang » thi nang, thu hang, thu bang
doc sach » hoc sach, nuoc sach, dac sac
cho hoc » co hoc
hieu va » lieu va, hieu qua
xuc van » duc van, luc van, vuc van
hanh di » hanh vi, hanh de, hang di
cua cau » cua cac, cua chu, cua cay
va cam » va cham, va cac, va cao
di cua » dai cua, doi cua, de cua

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) OR (doc sach)) thu nang ((cho hoc) or (khoa hoc)). hieu va cam xuc van hanh di cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) thu nang ((cho hoc) OR (khoa hoc)). hieu va cam xuc van hanh di cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) thu nang ((cho hoc) or (khoa hoc)). hieu va cam xuc van hanh di cua cau*".