List unique values from multiple columns

Hello,

I am kind of new in advanced programming with Excel.

I have a table that gathers a number of sentences which I classify with 3 category columns.

Eg.: Sentence / Category Level 1 / Category Level 2 / Category Level 3

This categories are different for each sentence, but they can repeat themselves across the 3 columns and in different levels.

What I'm trying to do is create one column in another worksheet that lists the values from those 3 columns without duplicated values.

Is this possible to do? How can I do this?

Thanks a lot in advance. I'll appreciate any kind of help. I really need it.

Best regards,

Socio