Perhaps you should try some spelling variations:
lang duong » lang dong, lang muong, lang tuong
duong manh » duong van
hien hanh » dieu hanh
trinh van » trinh han, trinh quan, trinh toan
manh toan » thanh toan, anh tuan, tinh toan
trinh va » trinh vat, trinh ve, trinh vi
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hien hanh - hanh ((trinh va) or (trinh van)) lang duong manh toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien hanh - hanh ((trinh va) OR (trinh van)) lang duong manh toan cao.
• Adding a wildcard symbol may retrieve word variants: hoc hien hanh - hanh ((trinh va) or (trinh van)) lang duong manh toan cao*.