Looking on the internet deeply has found these results:

the investigation of columns is the most popular phrase on the web.

the investigations of column 10 results on the web	the investigation of columns 13 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	Sometimes, as in the investigation of columns with a small radius, the basic assumption underlying the application of conventional processing algorithms�... Apr 30, 2014 ... Chromatographic optimization was done using the HPLC conditions and the investigation of columns with different packing materials, different�... As consecutive course of Reinforced concrete I, this course begins with the investigation of columns. Construction of interaction diagram of columns is one of �...

the investigations of column

10 results on the web

the investigation of columns

13 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

Sometimes, as in the investigation of columns with a small radius, the basic assumption underlying the application of conventional processing algorithms�...
Apr 30, 2014 ... Chromatographic optimization was done using the HPLC conditions and the investigation of columns with different packing materials, different�...
As consecutive course of Reinforced concrete I, this course begins with the investigation of columns. Construction of interaction diagram of columns is one of �...