References to objects:

obj-ref

<obj-ref> ( obj -- obj-ref )

References to assoc keys:

key-ref

<key-ref> ( assoc key -- key-ref )

References to assoc values:

value-ref

<value-ref> ( assoc key -- value-ref )

References to variables:

var-ref

<var-ref> ( var -- var-ref )

global-var-ref

<global-var-ref> ( var -- global-var-ref )

References to tuple slots:

slot-ref

<slot-ref> ( tuple slot -- slot-ref )

Using boxes as references:
Boxes as references