[…] Sapir […] is so dependent on form and intent upon finding formal differences supportig his conceptual grouping, that he indicates, as the only normal expression of his ‘concrete relational concepts’ […] affixation and inner modification, the use of the independent words being reserved to that of ‘pure relational concept’.
- Martinet (1962), a pag.99-100

Sapir further distinguishes between ‘pure relational concepts’ of the 'with' type, and ‘concrete relational concepts’, but he never makes perfectly clear where the difference between the two types actually lies.
- Martinet (1962), a pag.95