Sir

Misleading references in scientific papers are common where a research group has studied the same topic for many years.

I recently gave a course on the energy metabolism of Escherichia coli. In a paper published in 1996, the authors say: “For β-galactosidase assay, cells were grown in a glucose-containing minimal medium (pH 7.0) unless otherwise indicated4”.

Reference 4 is a paper from the same research group published in 1990. In this paper the sentence reads: “For the β-galactosidase assay, cells were grown in glucose (40 mM) minimal medium (pH 7.0) (ref. 13) unless otherwise indicated”.

Reference 13, published in 1985, reads: “For galactokinase assays and mRNA isolation, cells were grown in 50-ml volumes of glucose minimal medium32 supplemented with the indicated electron acceptor”.

Finally, the composition of the medium is given in reference 32.

This is a random example of a very bad habit. But why don't authors give the correct reference in every paper?