So apparently the AMS has a document on Ethical Guidelines. It’s actually remarkably well done. It has lots of tips that can help young mathematicians learn how to behave professionally. I was also impressed by the way that the guidelines avoid making too controversial of stands (which would go beyond the basics of ethics) while still not being milquetoast. For example, “No one should be exploited by the offer of a temporary position at an unreasonably low salary and/or an unreasonably heavy work load” is certainly an ethical obligation, but one that may be difficult to live up to.
I also thought that the guidelines about correct attribution were well phrased. For example:
To give appropriate credit, even to unpublished materials and announced results (because the knowledge that something is true or false is valuable, however it is obtained);
I have my own suggestion for a guideline on ethical use of citations: you should never ever use “et. al.” citations. Furthermore, if journal typesetters add them you should ask them to replace them with full citations.
If a bibliography just says “et al.” many readers are never going to get around to looking at the other names thereby effectively failing to properly attribute everyone. People at the end of the alphabet are already at enough of a professional disadvantage (see What’s in a Surname? The Effects of Surname Initials on Academic Success by Liran Einav and Leeat Yariv,), the use of “et al” just exacerbates this.
Hat tip: I learned about this document in a MathOverflow comment by Bill Johnson