The principal subscription databases for US law for holders of an Oxford SSO are
Note: Both Westlaw US and LexisLibrary have US legislation and case law, the Restatement of the Law of Unfair Competition, as well as commentary.
Subject searches for SOLO
Antitrust law -- United States
Competition, Unfair -- United States
Restraint of Trade -- United States
Standard SOLO searches will find both ebooks (two examples follow) and books - but the specialist book platforms which follow the books here may be worth searching independently
If you are looking for articles in US law journals, HeinOnline (and its Scholarcheck function) is also available to holders of an Oxford SSO.
The LawBod's current US collection is arranged according to Moys Classification system and shelved on Level 2. The works have U4 in their shelf marks.
A work on US law may be a Reading List title - such as the Posner below - so pay attention to SOLO results for mention of the Law Reserve Collection.
Older material eg previous editions may have USA at the beginning & (sec coll) after their shelf marks. These are available for you to read, but are on the Ground Floor.
Just ask a member of staff if you require any further directions when you are in the library.