Phage display library

A library of replicating entities, each entity comprises a recombinant vector comprising a randomized nucleic acid sequence, having the reading frame structure [NXX]n [CorAA] [NXX]m [NZZ]o, or [NZZ]o [NXX]m [CorAA] [NXX]n. Each NXX is independently a codon encoding for any amino acid except cysteine, CorAA is a codon encoding for cysteine or at least one other amino acid, each NZZ is independently a codon encoding for any amino acid, and n is an integer from 0 to 40, m is an integer from 1 to 20, o is an integer from 1 to 40, and at least 20 percent of CorAA encode for cysteine. The invention further relates to a set of recombinant vectors and to a set of randomized oligonucleotides, each oligonucleotide having said structure, as well as to a method for generating a library of replicating entities and to a method for identifying an amino acid polymer.