Reports of cases heard by the European Court of Human Rights can be found in the Internat section of the LawBod, upstairs on Floor 3.
European Commission of Human Rights, decisions and reports (D.R.) - Classmark: Internat 150 E41.
European Court of Human Rights, Series A: judgments and decisions (ECHR) - Classmark: Internat 150 E44
European Court of Human Rights Judgments (Decision and Pleadings, Series A & B) - Classmark: Internat 150 E45
European Court of Human Rights, Series B: Pleadings - Classmark: Internat 150 E45
European Human Rights Report (EHRR) - Classmark: Internat 150 E60.
On Floor 1 are reports with shelf marks beginning General.
For example: BHRC Butterworths human rights cases General 100 B90
In addition to the general law report series with which you will be accustomed from general law studies (eg AC, All ER,, WLR etc), citations may direct you to specialist series.
Law reports of the courts of England and Wales have shelfmarks starting Cw UK and are shelved on Floor 2. Holders of an Oxford SSO will find they have online access to most - but may well have to use both LexisLibrary and Westlaw Edge UK.