Perhaps you should try some spelling variations:
dung phuong » dung thuong, bang phuong, dung chung
phuong hinh » phuong binh, phuong linh, phuong dinh
chieu sang » chieu sach, chieu xanh, hieu lang
hieu sang » hieu lang, hieu quang, nhieu tang
hinh toan » tinh toan, thanh toan, trinh toan
trang va » hang va
tran van » luan van
toan tap » toan ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) OR (chieu sang)) - hanh ((trang va) or (tran van)) dung phuong hinh toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (chieu sang)) - hanh ((trang va) OR (tran van)) dung phuong hinh toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (chieu sang)) - hanh ((trang va) or (tran van)) dung phuong hinh toan tap".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (chieu sang)) - hanh ((trang va) or (tran van)) dung phuong hinh toan tap*.