Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
dau truc » cau truc, dai truc, doan truc
truc van » truc va, thuc van, truc ban
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
sach ty » sach y, sach tu, sach thu
de cua » le cua, te cua, dieu cua
di cua » dai cua, doi cua, do cua
va dau » va dao

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 ty ((nang ma) or (nang x)) hoi. lieu va dau truc van hanh ((di cua) OR (de cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang ma) OR (nang x)) hoi. lieu va dau truc van hanh ((di cua) OR (de cua)) te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang ma) or (nang x)) hoi. lieu va dau truc van hanh ((di cua) OR (de cua)) te*".