Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thien van » thi van
thu sach » tu sach, thuat sach, thu hoach
hieu van » hieu va, lieu va, hieu ve
lam luc » lao luc, lam duoc
luu tre » luu tru, cuu tre, luy tre
nang o » nang co, nang ho, nang ro
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi luu » vi lua
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (thuoc sach)) y nang o hoi. ((hieu van) or (thien van)) lam luc va dan vi luu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) y nang o hoi. ((hieu van) OR (thien van)) lam luc va dan vi luu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (thuoc sach)) y nang o hoi. ((hieu van) or (thien van)) lam luc va dan vi luu tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (thuoc sach)) y nang o hoi. ((hieu van) or (thien van)) lam luc va dan vi luu tre*.