How do I find information on papers in colData

[barbarashih]

I was wondering how I could find out more information (citations) for the columns labelled with "paper_" in colData? For instance, if I download the files using

project <- "TCGA-CHOL"
query_RNASeq <- GDCquery(project = project,          
    data.category = "Transcriptome Profiling" ,          
    data.type = "Gene Expression Quantification" ,          
    workflow.type = "STAR - Counts",
    experimental.strategy = "RNA-Seq" ,
    sample.type = "Primary Tumor")
RNAseq_samples <- getResults(query_RNASeq)

GDCdownload(query_RNASeq)
data_RNAseq <- GDCprepare(query_RNASeq)
sample_annotation <- colData(data_RNAseq)
colnames(sample_annotation )

What does "paper_8p_CHOL_del" or "paper_1" in colnames refer to?

Thank you Best wishes

Barbara