Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
dinh cuu » dinh chi
doc sach » toc sach, nuoc sach, dac sac
va danh » va dinh, va dan, va hanh
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
nang o » nang co, nang ho, nang ro
luc va » duc va, tuc va, loc va
v nang » va nang, vu nang, van nang
di cuu » di cau, di cua
o hoc » co hoc, mo hoc, so hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) or (doc sach)) v nang o hoc. hieu va cam luc va danh ((di cuu) OR (dinh cuu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (doc sach)) v nang o hoc. hieu va cam luc va danh ((di cuu) OR (dinh cuu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (doc sach)) v nang o hoc. hieu va cam luc va danh ((di cuu) OR (dinh cuu)) tre".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (doc sach)) v nang o hoc. hieu va cam luc va danh ((di cuu) OR (dinh cuu)) tre*.