Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cau tren » cu tren, dau tren, ca tren
toc sach » hoc sach, doc sach, thuoc sach
thuc va » thuc vat, thuc dan, thuc day
ve pham » vi pham, v pham, ve phan
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
ly nang » ky nang, ly hang, ly vang
hieu ve » hieu va, hieu van

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (toc sach)) ly nang xa hoi. hieu ve pham thuc va ((tinh toan) or (hang va)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ly nang xa hoi. hieu ve pham thuc va ((tinh toan) OR (hang va)) cau tren.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ly nang xa hoi. hieu ve pham thuc va ((tinh toan) or (hang va)) cau tren*.