add citations for ontologies

content/03.results.md

@@ -9,7 +9,7 @@ All samples on the Portal include a core set of metadata obtained from investiga
 Some investigators submitted additional metadata, such as treatment and tumor stage, which can also be found on the Portal.
 All submitted metadata was standardized to maintain consistency across projects before adding to the Portal.
 In addition to providing a human-readable value for the submitted metadata, we also provide an ontology term ID, if applicable.
-Submitted metadata was mapped to an associated ontology term IDs obtained from HsapDV (age), PATO (sex), NCBI taxonomy (organism), MONDO (disease), UBERON (tissue), and Hancestro (ethnicity, if applicable). 
+Submitted metadata was mapped to an associated ontology term IDs obtained from HsapDV (age) [@url:https://www.ebi.ac.uk/ols4/ontologies/hsapdv], PATO (sex)[@url:https://www.ebi.ac.uk/ols4/ontologies/pato], NCBI taxonomy (organism)[@url:https://www.ncbi.nlm.nih.gov/taxonomy], MONDO (disease)[@url:https://www.ebi.ac.uk/ols4/ontologies/mondo], UBERON (tissue)[@url:https://www.ebi.ac.uk/ols4/ontologies/uberon], and Hancestro (ethnicity, if applicable) [@url:https://www.ebi.ac.uk/ols4/ontologies/hancestro]. 
 Including ontology term IDs for each sample provides users with standardized metadata terms that can be used across all projects.
 
 The Portal contains data from 500 samples and over 50 tumor types.