Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
ty ngang » ly ngan, te ngan, ty xang
hanh de » hanh ve, hanh kem
luc van » luoc van, luu van, duc van
cac luc » cau luc, coc luc, cac nuoc
hieu ve » hieu va, hieu van
tho hoc » thao hoc, cho hoc, pho hoc
tu ngan » vu ngan, tu ngay, te ngan
cua cau » cua cac, cua chu, cua cay
ve cac » va cac, vien cac
de cua » le cua, te cua, dieu cua

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 (hoc sinh)) ((ty ngang) or (tu ngan)) tho hoc. hieu ve cac luc van hanh de cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc sinh)) ((ty ngang) OR (tu ngan)) tho hoc. hieu ve cac luc van hanh de cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc sinh)) ((ty ngang) or (tu ngan)) tho hoc. hieu ve cac luc van hanh de cua cau*".