You can find general basic information on reciprocity on Wikipedia. Some books on reciprocity are: Reciprocity, by Lawrence Baker, A cooperative species: Human reciprocity by Lawrence Baker, Trust and Reciprocity: Interdisciplinary Lessons for experimental research, by Elinor Ostrom.

Does virginia have reciprocity for tickets with delaware?

Reciprocity means that just as we would not like to be killed, robbed, abused and so forth, so would all other living beings not like to have these things happen to them. One can put this principle of reciprocity quite simply by saying "do not act towards others in a way which you would not want them to act towards you". Given these principles of equality and reciprocity, it is not hard to see how they stand behind, how they create the foundation for the rules of good conduct.

in the fraction 9/10 the positive reciprocity is 9

As far as I can tell, none.

Of the states that do offer reciprocity, all of them require that the state in which the attorney sits offer reciprocity to them, as well. SD does not allow reciprocity with any state, so no state will allow reciprocity with SD.