VIEW's on UNION's

I miss <subject>. I know the answer is that I can write them myself,
but I don't know where to start or end.

See this construct:
CREATE TABLE gl-amount (
glam_nr int,
period date,
entry_amount numeric(9,0),
PRIMARY KEY (glam_seq,period)
);

CREATE VIEW glam_curmth_v AS
SELECT entry_amount AS amount1 FROM gl-amount
WHERE date_part(year', period) = date_part('year', now::datetime)
AND date_part('month', period) = 1
UNION SELECT entry_amount AS amount2 FROM gl-amount
WHERE type = 'S' AND period = 2;

SELECT entry_amount AS amount1 FROM gl-amount
WHERE date_part('year', period) = date_part('year', 'now'::datetime)
AND date_part('month', period) = 1
UNION SELECT entry_amount AS amount2 FROM gl-amount
WHERE date_part('year', period) = date_part('year', 'now'::datetime)
AND date_part('month', period) = 2
...

Can it be done without the use of VIEW's on UNION's?