Perhaps you should try some spelling variations:
tan hanh » tan thanh, tang hanh, toan hanh
te sach » toc sach
cac duc » cac du, cao duc, cac dac
sach lo » sach dao, sach doi, sach hoi
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
ve cac » va cac, vien cac
di cua » dai cua, doi cua, do cua
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: te sach lo ((nang ma) or (tang ma)) hoi. hieu ve cac duc tan hanh ((di cua) OR (de cua)) tuc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach lo ((nang ma) OR (tang ma)) hoi. hieu ve cac duc tan hanh ((di cua) OR (de cua)) tuc*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach lo ((nang ma) or (tang ma)) hoi. hieu ve cac duc tan hanh ((di cua) OR (de cua)) tuc*".