Perhaps you should try some spelling variations:
trinh thiet » trinh viet, trinh thi
thiet qua » thien quan, hieu qua, thien quy
vien than » vien thanh, dien than, vien nhan
dien han » dien phan, dien than, dien dan
qua dan » qua danh, qua ban, cua dan
dan cua » dan ca, ban cua, dai cua
nha hoc » nha thuoc, khoa hoc, nha nuoc
ha hoc » hoa hoc, va hoc, ha hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: giao trinh thiet qua dan cua nguoi viet ((ha hoc) OR (nha hoc)) ((dien han) or (vien than))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: giao trinh thiet qua dan cua nguoi viet ((ha hoc) OR (nha hoc)) ((dien han) OR (vien than)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "giao trinh thiet qua dan cua nguoi viet ((ha hoc) OR (nha hoc)) ((dien han) or (vien than))".
• Adding a wildcard symbol may retrieve word variants: giao trinh thiet qua dan cua nguoi viet ((ha hoc) OR (nha hoc)) ((dien han) or (vien than))*.