When was the terminology *tracing collector* introduced to denote both mark-and-sweep and copy collectors Automatic storage reclamation, aka garbage collection, comes in two
main families, sometimes cooperating: the reference count collectors
and the tracing collectors. I may develop specifics of each family if
there is demand for it but my question is about tracing collectors.

Tracing collectors, in their simpler form can be divided into
mark-and-sweep (possibly with compaction) and copy collectors (that
compact naturally). Historically, they seem to have been
considered distinct families in the first 10 or 20 years of the
development of garbage collection technology.

I am wondering when they started to become known as tracing collectors
forming a single family. When was the expression tracing collectors
first used to denote both mark-and-sweep and copy collection, and
possibly collectors mixing both technologies (as is often the case with
generational collectors).

Ideally, a reference to a paper introducing the terminology would be
the best form for an answer. Reference to a book is good too, if you can give the printing where it first appears, as books often evolve with successive printings. Specifying the page or giving a quote would be nice too.

Added after accepting the answer.

I am accepting the answer given by Pseudonym, as it is a very clear
answer, that seems to be as good as it will ever get (but who
knows?). What I mean is that it seems unlikely that an earlier date
will be found, sinve the Paul Wilson's 1992 survey is pretty
thorough. As I recall, the previous survey by Cohen in 1981 does not
allude to tracing or unification of copy and mark-and-sweep.

An interesting trivia is that the introduction of this concept is
exactly half-way between the first garbage collection paper in 1960 (as
far as I know) and now (early 2015), which give a kind of time measure
of conceptual evolution.

This first GC papers, to my knowledge, used reference counting and
were published in 1960. According to wikipedia, which cites  Jones,
Richard; Lins, Rafael (1996), Garbage collection: algorithms for
automatic dynamic memory management, Wiley, p. 40, ISBN
9780471941484:


  The first, though cumbersome and error-prone, reference counting technique was described by J. Gelertner, J.R. Hansen, and C.L. Gerberich [Gelernter et al, 1960] but the standard reference counting algorithm is due to George Collins [Collins, 1960].


To my knowledge, the first tracing GC is a mark-and-sweep
implementation for LISP published in 1964 in, Notes on implementing
LISP for the M-460 Computer, Timothy P. Hart and Thomas G. Evans,
pp. 191-203 in The Programming Language LISP, its Operation and
Applications, March 1964, published by Information International, and
reprinted by MIT press (though they seemed to have lost all memory of
it when I asked, a long time ago). It does use the name "garbage collector", but I do not
know whether that is the first occurrence in the computer literature.
The terminology was introduced in Lang and Dupont, Incremental Incrementally Compacting Garbage Collection, SIGPLAN 87. This is the paper which consolidated several lines of enquiry into one common language.

The way I found this out was by consulting Paul Wilson's 1992 survey, Uniprocessor Garbage Collection Techniques, which is required reading if you need to know stuff like this.