What is ISBN UK, when Author is 'Dave Martin', and when ISBN US is 'N/A'?
CREATE TABLE table_46139 (
    "Title" text,
    "Author" text,
    "ISBN UK" text,
    "ISBN US" text,
    "TV companions featured" text
)
SELECT "ISBN UK" FROM table_46139 WHERE "Author" = 'dave martin' AND "ISBN US" = 'n/a'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is ISBN UK, when Author is 'Dave Martin', and when ISBN US is 'N/A'? ### Input: CREATE TABLE table_46139 (
    "Title" text,
    "Author" text,
    "ISBN UK" text,
    "ISBN US" text,
    "TV companions featured" text
) ### Response: SELECT "ISBN UK" FROM table_46139 WHERE "Author" = 'dave martin' AND "ISBN US" = 'n/a'