what is the {determination method} for {Cádiz} has {population} as {128554.0} ?
How did you know what the population of Cadiz was?
How was it determined that the population of Cadiz was 128,554?
SELECT ?u WHERE { ?s property:population ?k . resource:Cádiz property:population ?s . FILTER ( CONTAINS ( ?k , '128554.0' ) ) . ?s property:determination_method ?u }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q15682> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1082> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <128554.0> .
?statement <http://www.wikidata.org/entity/P459> ?value. 
} 

SELECT ?value WHERE { wd:Q15682 p:P1082 ?s . ?s ps:P1082 ?x filter(contains(?x , '128554.0')) . ?s pq:P459 ?value}