Also arrived were Poles, Russians, French (more than 100,000 each), Germans and Austrians (also more than 100,000), Portuguese, Greeks, Ukrainians, Croats, Czechs, Irish, British, Swiss, Dutch, Hungarians, Scandinavians (the vast majority being Danes ) , and people from other European and Middle Eastern countries, ...
since libro is masculine then the the color needs to have a masculine ending hence rojo not roja also its only one book so no need for the s at the end